Fabrication of electrochromic devices

ABSTRACT

Electrochromic devices and methods may employ the addition of a defect-mitigating insulating layer which prevents electronically conducting layers and/or electrochromically active layers from contacting layers of the opposite polarity and creating a short circuit in regions where defects form. In some embodiments, an encapsulating layer is provided to encapsulate particles and prevent them from ejecting from the device stack and risking a short circuit when subsequent layers are deposited. The insulating layer may have an electronic resistivity of between about 1 and 10 8  Ohm-cm. In some embodiments, the insulating layer contains one or more of the following metal oxides: aluminum oxide, zinc oxide, tin oxide, silicon aluminum oxide, cerium oxide, tungsten oxide, nickel tungsten oxide, and oxidized indium tin oxide. Carbides, nitrides, oxynitrides, and oxycarbides may also be used.

INCORPORATION BY REFERENCE

An Application Data Sheet is filed concurrently with this specificationas part of the present application. Each application that the presentapplication claims benefit of or priority to as identified in theconcurrently filed Application Data Sheet is incorporated by referenceherein in its entirety and for all purposes.

BACKGROUND

Electrochromism is a phenomenon in which a material exhibits areversible electrochemically-mediated change in an optical property whenplaced in a different electronic state, typically by being subjected toa voltage change. The optical property is typically one or more ofcolor, transmittance, absorbance, and reflectance. Electrochromicmaterials may be incorporated into, for example, windows and mirrors.The color, transmittance, absorbance, and/or reflectance of such windowsand mirrors may be changed by inducing a change in the electrochromicmaterial. However, advances in electrochromic technology, apparatus, andrelated methods of making and/or using them, are needed becauseconventional electrochromic windows suffer from, for example, highdefectivity and low versatility.

SUMMARY

Disclosed herein is an electrochromic device design and process forproducing electrochromic devices. In some embodiments, the devices andmethods employ the addition of a defect-mitigating insulating layerwhich prevents electronically conducting layers and/orelectrochromically active layers from contacting layers of the oppositepolarity and creating a short circuit in regions where defects form. Insome embodiments, an encapsulating layer is provided to encapsulateparticles and prevent them from ejecting from the device stack andrisking a short circuit when subsequent layers are deposited. In certainembodiments, the insulating layer has an electronic resistivity ofbetween about 1 and 5×10¹⁰ Ohm-cm. In certain embodiments, theinsulating layer contains one or more of the following metal oxides:cerium oxide, titanium oxide, aluminum oxide, zinc oxide, tin oxide,silicon aluminum oxide, tungsten oxide, nickel tungsten oxide, tantalumoxide, and oxidized indium tin oxide. In certain embodiments, theinsulating layer contains a nitride, carbide, oxynitride, or oxycarbidesuch as nitride, carbide, oxynitride, or oxycarbide analogs of thelisted oxides. As an example, the insulating layer includes one or moreof the following metal nitrides: titanium nitride, aluminum nitride,silicon nitride, and tungsten nitride. The insulating layer may alsocontain a mixture or other combination of oxide and nitride materials(e.g., a silicon oxynitride).

One aspect of this disclosure concerns electrochromic devicescharacterized by the following features: (a) a substrate; (b) a firstelectrode layer disposed on the substrate, the first electrode layercomprising a first transparent electronically conductive material; (c)an electrochromic stack comprising an electrochromic layer ofelectrochromic material and a counter electrode layer of counterelectrode material; (d) a second electrode layer disposed on theelectrochromic stack, the second electrode layer comprising a secondtransparent electronically conductive material; and (e) adefect-mitigating insulating layer comprising a substantiallytransparent and electronically insulating material. The insulatingmaterial is disposed at (i) a location between an intermediate positionwithin the electrochromic layer and the position of the electrode layerto which the electrochromic layer is in most direct electricalcommunication or (ii) a location between an intermediate position withinthe counter electrode layer and the position of the electrode layer towhich the counter electrode layer is in the most direct electricalcommunication. In some implementations, the electrochromic stack has agraded composition.

In certain embodiments, the electrochromic material is a cathodicallycoloring electrochromic material and the counter electrode material isan anodically coloring electrochromic material. The electrochromic layeris adjacent to the first electrode layer and the counter electrode layeris adjacent to the second electrode layer. The electrochromic materialmay be a tungsten oxide. The counter electrode material may be a nickeltungsten oxide. The electrochromic stack may also include an ionconducting layer interposed between the electrochromic layer and thecounter electrode layer.

In such embodiments, the defect-mitigating insulating layer may belocated at various positions in the device. For example, the insulatinglayer may be disposed at a location between an intermediate positionwithin the counter electrode layer and the position of the secondelectrode layer. In some cases, the insulating layer is disposed at anintermediate position within the counter electrode layer. In some cases,the defect-mitigating insulating layer is disposed between the counterelectrode layer and the second electrode layer, in contact with thesecond electrode layer.

In certain embodiments, the electrochromic material is a cathodicallycoloring electrochromic material and the counter electrode material isan anodically coloring electrochromic material, and the electrochromiclayer is adjacent to the second electrode layer, and the counterelectrode layer is adjacent to the first electrode layer. In some suchembodiments, the defect-mitigating insulating layer is disposed at alocation between an intermediate position within the electrochromiclayer and the position of the second electrode layer. In otherembodiments, the defect-mitigating insulating layer is disposed at anintermediate position within the electrochromic layer. In still otherembodiments, the defect-mitigating insulating layer is disposed betweenthe electrochromic layer and the second electrode layer, in contact withthe second electrode layer.

In some implementations, the electrochromic stack does not contain aseparately deposited ion conductor layer. In some implementations, thenumber of visible short-related pinhole defects in the electrochromicdevice is no greater than about 0.005 per square centimeter. In somecases, the electrochromic stack is entirely solid state and inorganic.

The electrochromic device may additionally include a seconddefect-mitigating insulating layer proximate the first electrode layer.In such devices, both defect-mitigating insulating layers may bedisposed between the first and second electrode layers.

In some implementations, the substrate contains only glass or otherstructural member. In such cases, the first electrode directly contactsthe substrate. In other implementations, the device includes one or morelayers between the substrate and the first electrode layer. For example,one of the layers between the substrate and the first electrode layermay be a diffusion barrier layer.

In some embodiments, the electrochromic layer contains two sub-layerseach containing tungsten oxide, and one sub-layer has a greaterconcentration of oxygen than the other sub-layer. As an example, thecounter electrode layer in such embodiments is a nickel tungsten oxide.

The defect-mitigating insulating layer may be made from variousmaterials and have various properties. In some embodiments, thedefect-mitigating insulating layer is a metal oxide, a metal nitride, ametal carbide, a metal oxynitride, or a metal oxycarbide. For example,the defect-mitigating insulating layer may be a metal oxide selectedfrom the group consisting of aluminum oxide, titanium oxide, tantalumoxide, cerium oxide, zinc oxide, tin oxide, silicon aluminum oxide,tungsten oxide, nickel tungsten oxide, and oxidized indium tin oxide.Alternatively, the defect-mitigating insulating layer may be a metalnitride selected from the group consisting of titanium nitride, aluminumnitride, silicon nitride, tantalum nitride, and tungsten nitride. Stillfurther, the defect-mitigating insulating layer may be a metal carbideselected from the group consisting of titanium carbide, aluminumcarbide, silicon carbide, tantalum carbide, and tungsten carbide. Insome devices, the defect-mitigating insulating layer contains twodistinct electronically insulating materials. For example, thedefect-mitigating insulating layer may include particles of a polishingcompound.

The defect-mitigating insulating layer may be between about 5 nm and 500nm in thickness. In certain embodiments, the insulating layer has anelectronic resistivity of between about 1 ohm-cm and 10¹⁵ ohm-cm. Incertain embodiments, the defect-mitigating insulation layer is ionicallyconductive.

Another aspect of the disclosure concerns methods of fabricating anelectrochromic device characterized by the following operations: (a)forming an electrochromic stack on a first electrode layer disposed on asubstrate, wherein the electrochromic stack includes an electrochromiclayer of electrochromic material and a counter electrode layer ofcounter electrode material, and wherein the first electrode layercontains a first transparent electronically conductive material; (b)forming a defect-mitigating insulating layer within, beneath, or on theelectrochromic stack, wherein the defect-mitigating insulating layerincludes a substantially transparent and electronically insulatingmaterial; and (c) forming a second electrode layer over theelectrochromic stack, the second electrode layer comprising a secondtransparent electronically conductive material. The defect-mitigatinginsulating layer is disposed at (i) a location between an intermediateposition within the electrochromic layer and the position of theelectrode layer to which the electrochromic layer is in most directelectrical communication or (ii) a location between an intermediateposition within the counter electrode layer and the position of theelectrode layer to which the counter electrode layer is in the mostdirect electrical communication.

In some implementations, the electrochromic layer contains acathodically coloring electrochromic material and is formed before thecounter electrode layer in the electrochromic stack. In some suchimplementations, the defect-mitigating insulating layer is formedbetween the electrochromic layer and the first electrode layer, incontact with the first electrode layer. In other implementations, thedefect-mitigating insulating layer is formed between the counterelectrode layer and the second electrode layer, in contact with thesecond electrode layer. In other cases, the defect-mitigating insulatinglayer is formed within the counter electrode layer. In still otherimplementations, the defect-mitigating insulating layer is formed withinthe electrochromic layer. In some such implementations, the processadditionally includes forming or polishing a second defect-mitigatinginsulating layer between the first electrode layer and theelectrochromic layer.

In some embodiments, the electrochromic layer contains a cathodicallycoloring electrochromic material and is formed after the counterelectrode layer in the electrochromic stack. In some such embodiments,the process additionally includes forming or polishing a seconddefect-mitigating insulating layer between the first electrode layer andthe counter electrode layer. In some such embodiments, thedefect-mitigating insulating layer is formed between the electrochromiclayer and the second electrode layer, in contact with the secondelectrode layer. In other embodiments, the defect-mitigating insulatinglayer is formed within the electrochromic layer. In still otherembodiments, the defect-mitigating insulating layer is formed within thecounter electrode layer. In still other embodiments, thedefect-mitigating insulating layer is formed between the counterelectrode layer and the first electrode layer, in contact with the firstelectrode layer.

In certain embodiments, the operation of forming the electrochromicstack is performed without depositing an ion conducting layer. Incertain embodiments, the electrochromic stack is entirely solid stateand inorganic. For example, the electrochromic material may be atungsten oxide. In some processes, the counter electrode material is anickel tungsten oxide. In some methods, forming the electrochromic stackincludes forming an electrochromic layer having two sub-layers eachcomprising tungsten oxide, but with different levels of oxygen.

The methods may deposit defect-mitigating insulating layers of varioustypes. In some embodiments, the defect-mitigating insulating layer is ametal oxide, a metal nitride, a metal carbide, a metal oxynitride, or ametal oxycarbide. For example, the defect-mitigating insulating layermay be a metal oxide selected from the group consisting of aluminumoxide, titanium oxide, tantalum oxide, cerium oxide, zinc oxide, tinoxide, silicon aluminum oxide, tungsten oxide, nickel tungsten oxide,and oxidized indium tin oxide. Alternatively, the defect-mitigatinginsulating layer may be a metal nitride selected from the groupconsisting of titanium nitride, aluminum nitride, silicon nitride,tantalum nitride, and tungsten nitride. Still further, thedefect-mitigating insulating layer may be a metal carbide selected fromthe group consisting of titanium carbide, aluminum carbide, siliconcarbide, tantalum carbide, and tungsten carbide. In some devices, thedefect-mitigating insulating layer contains two distinct electronicallyinsulating materials. For example, the defect-mitigating insulatinglayer may include particles of a polishing compound. In some cases, theinsulating layer has an electronic resistivity of between about 1 ohm-cmand 10¹⁵ ohm-cm.

Forming the defect-mitigating insulating layer may include forming twodistinct electronically insulating materials. For example, forming thedefect-mitigating insulating layer may include polishing an insulatinglayer on the substrate as provided to the process, where one of theelectronically insulating materials contains particles of a polishingcompound. In some such examples, the insulating layer on the substratecontains titanium dioxide. In some embodiments, forming thedefect-mitigating insulating layer involves polishing the firstelectrode layer on the substrate, and the electronically insulatingmaterial of the defect-mitigating insulating layer contains particles ofa polishing compound.

In some methods, one or more layers are disposed between the substrateand the first electrode layer. For example, one of the layers betweenthe substrate and the first electrode layer may be a diffusion barrierlayer.

In certain embodiments, the methods additionally include forming asecond defect-mitigating insulating layer. Both defect-mitigatinginsulating layers may be disposed between the first and second electrodelayers.

In various implementations, the methods additionally include depositinglithium on at least a portion of the electrochromic stack. In somecases, depositing lithium is performed prior to forming thedefect-mitigating insulating layer.

Another aspect of the disclosure concerns electrochromic devicescharacterized by the following elements: (a) a substrate; (b) a firstelectrode layer disposed on the substrate, the first electrode layercomprising a first transparent electronically conductive material; (c)an electrochromic stack comprising an electrochromic layer ofelectrochromic material and a counter electrode layer of counterelectrode material, wherein the first electrode layer is between thesubstrate and the electrochromic stack; (d) a second electrode layerdisposed on the electrochromic stack such that the electrochromic stackis disposed between the first electrode layer and the second electrodelayer, the second electrode layer comprising a second transparentelectronically conductive material; and (e) a defect-mitigatinginsulating layer that is substantially transparent and electronicallyinsulating, wherein the defect-mitigating insulating layer is disposedbetween the first electrode layer and the electrochromic stack. Invarious implementations, the electrochromic devices contain a seconddefect-mitigating insulating layer, which second defect-mitigatinginsulating layer is disposed on or in the electrochromic stack.

In devices of this aspect of the disclosure, the defect-mitigatinginsulating layer may be made from various materials and have variousproperties. In some embodiments, the defect-mitigating insulating layeris a metal oxide, a metal nitride, a metal carbide, a metal oxynitride,or a metal oxycarbide. For example, the defect-mitigating insulatinglayer may be a metal oxide selected from the group consisting ofaluminum oxide, titanium oxide, tantalum oxide, cerium oxide, zincoxide, tin oxide, silicon aluminum oxide, tungsten oxide, nickeltungsten oxide, and oxidized indium tin oxide. Alternatively, thedefect-mitigating insulating layer may be a metal nitride selected fromthe group consisting of titanium nitride, aluminum nitride, siliconnitride, tantalum nitride, and tungsten nitride. Still further, thedefect-mitigating insulating layer may be a metal carbide selected fromthe group consisting of titanium carbide, aluminum carbide, siliconcarbide, tantalum carbide, and tungsten carbide. In some devices, thedefect-mitigating insulating layer contains two distinct electronicallyinsulating materials. For example, the defect-mitigating insulatinglayer may include particles of a polishing compound. In variousembodiments of this aspect, the defect-mitigating insulating layer isbetween about 5 nm and 100 nm thick.

In some cases, the defect-mitigating insulating layer contains titaniumoxide or tin oxide. In some cases, the defect-mitigating insulatinglayer contains particles of a polishing compound. In some cases, thedefect-mitigating insulating layer contains two distinct electronicallyinsulating materials.

A further aspect of the disclosure concerns electrochromic devicescharacterized by the following elements: (a) a substrate; (b) a firstelectrode layer disposed on the substrate, the first electrode layercomprising a first transparent electronically conductive material; (c)an electrochromic stack comprising an electrochromic layer ofelectrochromic material and a counter electrode layer of counterelectrode material, wherein the first electrode layer is between thesubstrate and the electrochromic stack; (d) a second electrode layerdisposed on the electrochromic stack such that the electrochromic stackis disposed between the first electrode layer and the second electrodelayer, the second electrode layer comprising a second transparentelectronically conductive material; and (e) a defect-mitigatinginsulating layer that is substantially transparent and electronicallyinsulating, wherein the defect-mitigating insulating layer is disposedbetween the second electrode layer and the electrochromic stack. Incertain embodiments, the second electrode layer contains indium tinoxide.

In devices of this aspect of the disclosure, the defect-mitigatinginsulating layer may be made from various materials and have variousproperties. In some embodiments, the defect-mitigating insulating layeris a metal oxide, a metal nitride, a metal carbide, a metal oxynitride,or a metal oxycarbide. For example, the defect-mitigating insulatinglayer may be a metal oxide selected from the group consisting ofaluminum oxide, titanium oxide, tantalum oxide, cerium oxide, zincoxide, tin oxide, silicon aluminum oxide, tungsten oxide, nickeltungsten oxide, and oxidized indium tin oxide. Alternatively, thedefect-mitigating insulating layer may be a metal nitride selected fromthe group consisting of titanium nitride, aluminum nitride, siliconnitride, tantalum nitride, and tungsten nitride. Still further, thedefect-mitigating insulating layer may be a metal carbide selected fromthe group consisting of titanium carbide, aluminum carbide, siliconcarbide, tantalum carbide, and tungsten carbide. In some devices, thedefect-mitigating insulating layer contains two distinct electronicallyinsulating materials. For example, the defect-mitigating insulatinglayer may include particles of a polishing compound. In variousembodiments of this aspect, the defect-mitigating insulating layer isbetween about 5 nm and 100 nm thick.

In various embodiments, the defect-mitigating insulating layer isbetween about 5 nm and 500 nm thick. In various embodiments, thedefect-mitigating insulation layer is ionically conductive. In someimplementations, the device includes a second defect-mitigatinginsulating layer, which second defect-mitigating insulating layer isdisposed beneath or in the electrochromic stack.

Another aspect of the disclosure pertains to methods of fabricating anelectrochromic device, which methods are characterized by the followingoperations: (a) receiving a substrate in sputter deposition apparatus,(b) forming an electrochromic stack on the substrate, and (c) forming asecond electrode layer over the electrochromic stack, the secondelectrode layer comprising a second transparent electronicallyconductive material. The electrochromic stack includes an electrochromiclayer of electrochromic material and a counter electrode layer ofcounter electrode material. The substrate received in the depositionapparatus includes a first electrode layer and a defect-mitigatinginsulating layer formed thereon, and the first electrode layer isdisposed between the substrate and the defect-mitigating insulatinglayer, and the first electrode layer includes a first transparentelectronically conductive material. The insulating layer iselectronically insulating and substantially transparent. In someembodiments, the methods additionally include forming a seconddefect-mitigating insulating layer in or on the electrochromic stack.

The methods may additionally include polishing the defect-mitigatinginsulating layer prior to forming the electrochromic stack on asubstrate. Polishing may optionally be performed prior to deposition ofthe defect-mitigating insulating layer as well as after. In oneembodiment, polishing is performed only after deposition of thedefect-mitigating insulating layer. As a result polishing, before and/orafter deposition of the layer, the defect-mitigating insulating layermay include particles of a polishing compound. A further discussion ofpolishing is found in PCT International Application No.PCT/US2012/057606 filed Sep. 28, 2012, which is incorporated herein byreference in its entirety.

The defect-mitigating insulating layer produced during the methods ofthis aspect may contain a metal oxide, metal nitride, a metal carbide, ametal oxynitride, or a metal oxycarbide. Examples of suchdefect-mitigating insulating materials include metal oxides selectedfrom the group consisting of aluminum oxide, cerium oxide, zinc oxide,tin oxide, silicon aluminum oxide, tungsten oxide, nickel tungstenoxide, and oxidized indium tin oxide. In some cases, thedefect-mitigating insulating layer contains particles of a polishingcompound. In some cases, the defect-mitigating insulating layer isbetween about 5 and 100 nm thick.

Another aspect of the disclosure concerns apparatus for fabricating anelectrochromic device, which apparatus is characterized by an integrateddeposition system comprising: (i) a first deposition station containinga first target comprising a first material for depositing a layer of anelectrochromic material on a substrate when the substrate is positionedin the first deposition station, (ii) a second deposition stationcontaining a second target comprising a second material for depositing alayer of a counter electrode material on the substrate when thesubstrate is positioned in the second deposition station, and (iii) athird deposition station configured to deposit a defect-mitigatinginsulating layer that is electronically insulating and substantiallytransparent. The apparatus is also characterized by a controllercontaining program instructions for passing the substrate through thefirst and second deposition stations in a manner that sequentiallydeposits a stack on the substrate, the stack comprising the layer ofelectrochromic material, the layer of counter electrode material, andthe defect-mitigating insulating layer.

Such apparatus may additionally include a fourth deposition stationconfigured to deposit an electrode layer on the stack, wherein theelectrode layer contains a transparent electronically conductivematerial. In some implementations, the apparatus additionally include alithium deposition station containing a lithium target for depositinglithium on or within the layer of electrochromic material or on orwithin the layer of counter electrode material when the substrate ispositioned in the lithium deposition station.

In certain embodiments, the program instructions include instructionsfor depositing the defect-mitigating insulating layer at (i) a locationbetween an intermediate position within the electrochromic layer and theposition of the electrode layer to which the electrochromic layer is inmost direct electrical communication or (ii) a location between anintermediate position within the counter electrode layer and theposition of the electrode layer to which the counter electrode layer isin the most direct electrical communication.

Yet another aspect of the disclosure pertains to apparatus forfabricating an electrochromic device, which apparatus is characterizedby an integrated deposition system comprising: (i) a first depositionstation containing a first target comprising a first material fordepositing a layer of an electrochromic material on a substrate when thesubstrate is positioned in the first deposition station, (ii) a seconddeposition station containing a second target comprising a secondmaterial for depositing a layer of a counter electrode material on thesubstrate when the substrate is positioned in the second depositionstation, and (iii) a polisher configured to polish a defect-mitigatinginsulating layer on the substrate. The apparatus is also characterizedby a controller containing program instructions for passing thesubstrate through the first and second deposition stations in a mannerthat sequentially deposits a stack on the substrate, the stackcomprising the layer of electrochromic material and the layer of counterelectrode material. In some designs, the polisher is configured toincorporate electronically resistive particles in the defect-mitigatinginsulating layer.

Such apparatus may additionally include a third deposition stationconfigured to deposit an electrode layer on the stack, wherein theelectrode layer includes a transparent electronically conductivematerial. Further, such apparatus may additionally include a lithiumdeposition station containing a lithium target for depositing lithium onor within the layer of electrochromic material or on or within the layerof counter electrode material when the substrate is positioned in thelithium deposition station.

These and other features and advantages of the disclosed embodimentswill be described in more detail below with reference to the associatedrawings.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1A and 1B depict the structure and function of electrochromicdevices.

FIG. 2 depicts a particle defect in an electrochromic device.

FIGS. 3A-3D depict aspects of formation and remediation of a pop-offdefect.

FIG. 4A depicts an electrochromic device in which a defect-mitigatinginsulating layer is disposed between a second (e.g., upper) transparentconductive layer and the later formed of the counter electrode layer andthe electrochromic layer.

FIG. 4B depicts an electrochromic device in which an insulating layer isdisposed between two portions of a counter electrode layer (oralternatively between two portions of an electrochromic layer, if theelectrochromic layer is formed on top of the counter electrode layer).

FIG. 4C depicts an electrochromic device in which a defect-mitigatinginsulating layer is disposed between a second (e.g., upper) transparentconductive layer and the later formed of the counter electrode layer andthe electrochromic layer, and where the insulating layer is a modifiedform (more electronically resistive) of the counter electrode layer (orelectrochromic layer).

FIG. 4D depicts an electrochromic device having two defect-mitigatinginsulating layers and no ion conducting layer deposited between theelectrochromic and counter electrode layers.

FIG. 4E depicts an electrochromic device in which a defect-mitigatinginsulating layer encapsulates a particle.

FIG. 4F depicts a graded electrochromic device having adefect-mitigating layer embedded therein.

FIGS. 4G-4O are scanning electron micrographs of an electrochromicdevice illustrating different positions of a defect-mitigatinginsulating layer within a device stack.

FIG. 5A is a flow chart of a baseline process for forming anelectrochromic device that may be modified by introduction of one ormore defect-mitigating insulating layers.

FIGS. 5B and 5C are flow charts of processes that incorporate formationof a defect-mitigating insulating layer at specified locations in thesequence of device fabrication operations.

FIG. 5D is a flow chart of a process in accordance with certainembodiments in which first and second defect-mitigating insulatinglayers are formed adjacent to the transparent conductive layers.

FIG. 5E is a flow chart of a process in accordance with certainembodiments in which a transparent conductive layer and adefect-mitigating insulating layer is provided on a substrate.

DETAILED DESCRIPTION

The present disclosure concerns methods and apparatus for reducingdifficulties created by defects in electrochromic devices. Certain typesof defects introduce short circuits that produce particularlyunattractive blemishes in electrochromic products. Various disclosedembodiments concern the insertion of an additional layer in theelectrochromic device stack. This additional layer serves the primaryrole of providing an insulating layer between two conductive layers thatmight otherwise short circuit if a particle has been ejected from thedevice stack during fabrication. The problem of shorting associated withparticle ejection is described below in the context of FIGS. 3A-3D.

In one implementation, a resistive layer, sometimes referred to as adefect-mitigating insulating layer, is deposited in a process operationthat is the next operation after the execution of an operation that hasa propensity to cause particle ejections. An example of a particleejection step is the introduction of lithium metal into the device stack(sometimes referred to herein as lithiation). In some cases, aninsulating layer is deposited to encapsulate particles deposited duringfabrication. Encapsulated particles are less likely than unencapsulatedparticles to eject from a partially fabricated device stack and lead toa short circuit.

Electrochromic Devices—Examples

Before turning to a more detailed description of the insulating layerand processes incorporating insulating layer deposition, examples ofelectrochromic device structure and fabrication will be presented. FIGS.1A and 1B are schematic cross-sections of an electrochromic device, 100,showing a common structural motif for such devices. Electrochromicdevice 100 includes a substrate 102, a conductive layer (CL) 104, anelectrochromic layer (EC) 106, an optional ion conducting(electronically resistive) layer (IC) 108, a counter electrode layer(CE) 110, and another conductive layer (CL) 112. Elements 104, 106, 108,110, and 112 are collectively referred to as an electrochromic stack,114. A voltage source, 116, operable to apply an electric potentialacross electrochromic stack 112 effects the transition of theelectrochromic device from, e.g., a bleached state (refer to FIG. 1A) toa colored state (refer to FIG. 1B).

The order of layers may be reversed with respect to the substrate. Thatis, the layers may be in the following order: substrate, conductivelayer, counter electrode layer, ion conducting layer, electrochromicmaterial layer, and conductive layer. The counter electrode layer mayinclude a material that is electrochromic or not. If both theelectrochromic layer and the counter electrode layer employelectrochromic materials, one of them should be a cathodically coloringmaterial and the other should be an anodically coloring material. Forexample, the electrochromic layer may employ a cathodically coloringmaterial and the counter electrode layer may employ an anodicallycoloring material. This is the case when the electrochromic layer is atungsten oxide and the counter electrode layer is a nickel tungstenoxide.

The conductive layers commonly comprise transparent conductivematerials, such as metal oxides, alloy oxides, and doped versionsthereof, and are commonly referred to as “TCO” layers because they aremade from transparent conducting oxides. In general, however, thetransparent layers can be made of any transparent, electronicallyconductive material that is compatible with the device stack. Some glasssubstrates are provided with a thin transparent conductive oxide layersuch as fluorinated tin oxide, sometimes referred to as “TEC.”

Device 100 is meant for illustrative purposes, in order to understandthe context of embodiments described herein. Methods and apparatusdescribed herein are used to identify and reduce defects inelectrochromic devices, regardless of the structural arrangement of theelectrochromic device.

During normal operation, an electrochromic device such as device 100reversibly cycles between a bleached state and a colored state. Asdepicted in FIG. 1A, in the bleached state, a potential is appliedacross the electrodes (transparent conductor layers 104 and 112) ofelectrochromic stack 114 to cause available ions (e.g. lithium ions) inthe stack to reside primarily in the counter electrode 110. Ifelectrochromic layer 106 contains a cathodically coloring material, thedevice is in a bleached state. In certain electrochromic devices, whenloaded with the available ions, counter electrode layer 110 can bethought of as an ion storage layer.

Referring to FIG. 1B, when the potential on the electrochromic stack isreversed, the ions are transported across ion conducting layer 108 toelectrochromic layer 106 and cause the material to enter the coloredstate. Again, this assumes that the optically reversible material in theelectrochromic device is a cathodically coloring electrochromicmaterial. In certain embodiments, the depletion of ions from the counterelectrode material causes it to color also as depicted. In other words,the counter electrode material is anodically coloring electrochromicmaterial. Thus, layers 106 and 110 combine to synergistically reduce theamount of light transmitted through the stack. When a reverse voltage isapplied to device 100, ions travel from electrochromic layer 106,through the ion conducting layer 108, and back into counter electrodelayer 110. As a result, the device bleaches.

Some pertinent examples of electrochromic devices are presented in thefollowing US patent applications, each incorporated by reference in itsentirety: U.S. patent application Ser. No. 12/645,111, filed Dec. 22,2009; U.S. patent application Ser. No. 12/772,055, filed Apr. 30, 2010;U.S. patent application Ser. No. 12/645,159, filed Dec. 22, 2009; U.S.patent application Ser. No. 12/814,279, filed Jun. 11, 2010; and U.S.patent application Ser. No. 13/462,725, filed May 2, 2012.

Electrochromic devices such as those described in relation to FIGS. 1Aand 1B are used in, for example, electrochromic windows. For example,substrate 102 may be architectural glass upon which electrochromicdevices are fabricated. Architectural glass is glass that is used as abuilding material. Architectural glass is typically used in commercialbuildings, but may also be used in residential buildings, and typically,though not necessarily, separates an indoor environment from an outdoorenvironment. In certain embodiments, architectural glass is at least 20inches by 20 inches, and can be much larger, e.g., as large as about 72inches by 120 inches.

As larger and larger substrates are used for electrochromic windows itis desirable to minimize defects in the electrochromic device, becauseotherwise the performance and visual quality of the electrochromicwindows will suffer. The embodiments described herein may mitigatedefectivity in electrochromic windows.

In some embodiments, electrochromic glass is integrated into aninsulating glass unit (IGU). An insulating glass unit includes multipleglass panes assembled into a unit, generally with the intention ofmaximizing the thermal insulating properties of a gas contained in thespace formed by the unit while at the same time providing clear visionthrough the unit. Insulating glass units incorporating electrochromicglass are similar to insulating glass units currently known in the art,except for electrical terminals for connecting the electrochromic glassto voltage source.

Defectivity in Electrochromic Devices

As used herein, the term “defect” refers to a defective point or regionof an electrochromic device. Typically, defects are electrical shorts orpinholes. Further, defects may be characterized as visible ornon-visible. In general, a defect in an electrochromic device, andsometimes an area around the defect, does not change optical state(e.g., color) in response to an applied potential that is sufficient tocause non-defective regions of the electrochromic device to color orotherwise change optical state. Often a defect will be manifest asvisually discernible anomalies in the electrochromic window or otherdevice. Such defects are referred to herein as “visible” defects. Otherdefects are so small that they are not visually noticeable to theobserver in normal use (e.g., such defects do not produce a noticeablelight point or “pinhole” when the device is in the colored state duringdaytime).

A short is a localized electronically conductive pathway spanning theion conducting layer (e.g., an electronically conductive pathway betweenthe two transparent conducting layers). Typically, a defect causing avisible short will have a physical dimension on the order of tensmicrometers, sometimes less, which is a relatively small defect from avisual perspective. However, these relatively small defects result in avisual anomaly, the “halo”, in the colored electrochromic window thatare, for example, about 1 centimeter in diameter, sometimes larger.Halos can be reduced significantly by isolating the defect, for exampleby circumscribing the defect via a laser scribe or by ablating thematerial directly without circumscribing it. For example, a circular,oval, triangular, rectangular, or other shaped perimeter is ablatedaround the shorting defect thus electrically isolating it from the restof the functioning device. The circumscription may be only tens, ahundred, or up to a few hundred micrometers in diameter. Bycircumscribing, and thus electrically isolating the defect, the visibleshort will resemble only a small point of light to the naked eye whenthe window is colored and there is sufficient light on the other side ofthe window. When ablated directly, without circumscription, thereremains no EC device material in the area where the electrical shortdefect once resided. Rather, there is a hole through the device and atthe base of the hole is, for example, the float glass or the diffusionbarrier or the lower transparent electrode material, or a mixturethereof. Since these materials are all transparent, light may passthrough the base of the hole in the device. Depending on the diameter ofa circumscribed defect, and the width of the laser beam, circumscribedpinholes may also have little or no electrochromic material remainingwithin the circumscription (as the circumscription is typically, thoughnot necessarily, made as small as possible). Such mitigated shortdefects manifest as pin points of light against the colored device, thusthese points of light are commonly referred to as “pinholes.” Isolationof an electrical short by circumscribing or direct ablation would be anexample of an intentionally-made pinhole formed to convert a halo into amuch smaller visual defect. Pinholes may also arise as a natural resultof defects in the optical device. In either case, they are to be avoidedif possible.

A pinhole is a region where one or more layers of the electrochromicdevice are missing or damaged so that electrochromism is not exhibited.Pinholes are not electrical shorts, and, as described above, they may bethe result of mitigating an electrical short in the device. In certainembodiments, a pinhole has a defect dimension of between about 25micrometers and about 300 micrometers, typically between about 50micrometers and about 150 micrometers, thus it is much harder to discernvisually than a halo. Typically, in order to reduce the visibleperception of pinholes resulting from mitigation of halos, one willlimit the size of a purposely-created pinhole to about 100 micrometersor less.

In some cases, an electrical short is created by a conductive particlelodging in and/or across the ion conducting layer, thereby causing anelectronic path between the counter electrode layer and theelectrochromic layer or the transparent conducting layer associated witheither one of them. A defect may also be caused by a particle on thesubstrate on which the electrochromic stack is fabricated. When such aparticle causes layer delamination due to stresses imparted by theparticle, this is sometimes called “pop-off ” In other instances, thelayers do not adhere to the substrate properly and delaminate,interrupting the flow of ions and/or electrical current within thedevice. These types of defects are described in more detail below inrelation to FIGS. 2 and 3A-3D. A delamination or pop-off defect can leadto a short if it occurs before a transparent conducting layer orassociated EC or CE layer is deposited. In such cases, the subsequentlydeposited transparent conducting layer or EC/CE layer will directlycontact an underlying transparent conducting layer or CE/EC layerproviding direct electronic conductive pathway. A few examples of defectsources are presented in the table below. The table below is intended toprovide examples of mechanisms that lead to the different types ofvisible and non-visible defects. It is not exhaustive. Additionalfactors exist which may influence how the EC window responds to a defectwithin the stack.

Particle Location Worst Case Failure Effect on substrate pops offleaving pinhole pinhole on first pops off allowing TCL- visible shortTransparent TCL short voltage drop conductive layer on EC layer Pops offallowing TCL- visible short EC-TCL short voltage drop on IC layer popsoff leaving pinhole pinhole on CE layer pops off leaving pinhole pinhole

It is believed that problematic shorts are frequently those in which aparticle contacts the partially fabricated device before, during, orimmediately after a first electrochromic layer is deposited on asubstrate, and then remains in place until immediately before, during orafter deposition of the second transparent conductive layer. Asexplained more fully below, such shorts may be the result of particlesattached to the substrate upon entry into the electrochromic depositionchamber, or particles that become attached during deposition of acathodic electrochromic layer such as a layer of tungsten oxide orbecome attached immediately after deposition of the first electrochromiclayer but before any substantial amount of the next electrochromic layeris deposited. As explained, the substrate may or may not have atransparent conductive layer provided thereon when the substrate entersthe deposition apparatus. Problematic shorts may also be introduced byparticles that contact the partially fabricated device duringlithiation, such as lithiation performed after or during deposition ofthe second electrochromic layer.

As noted above, in the case of a visible short the defect will appear asa light central region (when the device is in the colored state) with adiffuse boundary such that the device gradually darkens with distancefrom the center of the short. If there are a significant number ofelectrical shorts (visible or non-visible) concentrated in an area of anelectrochromic device, they may collectively impact a broad region ofthe device whereby the device cannot switch in such region. This isbecause the potential difference between the EC and CE layers in suchregions cannot attain a threshold level required to drive ions acrossthe ion conductive layer. It should be understood that leakage currentmay result from sources other than short-type defects. Such othersources include broad-based leakage across the ion conducting layer andedge defects such as roll off defects and scribe line defects. Theemphasis here is on leakage caused only by points of electrical shortingacross the ion conducting layer in the interior regions of theelectrochromic device. These shorts cause visible defects that should beminimized for the electrochromic pane to be acceptable for use in anelectrochromic window. Conventionally, the visual defects are identifiedand mitigated prior to assembly of the pane into an IGU or mitigated inan IGU prior to assembly of the IGU in an architectural facade. However,these are expensive and time consuming procedures.

FIG. 2 is a schematic cross-section of an electrochromic device, 200,with a particle, 205, in the ion conducting layer causing a localizeddefect in the device. In this example, electrochromic device 200includes the same layers as described in relation to FIGS. 1A and 1B.Voltage source 116 is configured to apply a potential to electrochromicstack 114 as described above, through suitable connections (e.g., busbars) to conductive layers 104 and 112.

In this example, ion conducting layer 108 includes a conductiveparticle, 205, or other artifact causing a defect. Conductive particle205 results in a short between electrochromic layer 106 and counterelectrode layer 110. In this example, particle 205 spans the thicknessof the IC layer 108. Particle 205 physically impedes the flow of ionsbetween electrochromic layer 106 and counter electrode layer 110, andalso, due to its electrical conductivity, allows electrons to passlocally between the layers, resulting in a transparent region 210 inelectrochromic layer 106 and a transparent region 220 in counterelectrode layer 110. Transparent region 210 exists when the remainder oflayers 110 and 106 are in the colored state. That is, if electrochromicdevice 200 is in the colored state, conductive particle 205 rendersregions 210 and 220 of the electrochromic device unable to enter intothe colored state. Sometimes such visible defect regions are referred toas “constellations” or “halos” because they appear as a series of brightspots (or stars) against a dark background (the remainder of the devicebeing in the colored state). Humans will naturally direct theirattention to the halos and often find them distracting or unattractive.Embodiments described herein reduce such visible defects. Pinholedefects may or may not be deemed worthy of repair, as they can be nearlyindiscernible to the naked eye by most observers.

As mentioned above, visible short defects can also be caused byparticles popping off, e.g. during or after fabrication of theelectrochromic device, thereby creating damaged areas in theelectrochromic stack, through one or more layers of the stack. Pop-offdefects are described in more detail below.

FIG. 3A is a schematic cross-section of an electrochromic device, 300,with a particle 305 or other debris on conductive layer 104 prior todepositing the remainder of the electrochromic stack. Electrochromicdevice 300 includes the same components as electrochromic device 100.Particle 305 causes the layers in the electrochromic stack 114 to bulgein the region of particle 305, due to conformal layers 106-110 beingdeposited sequentially over particle 305 as depicted (in this example,conductive layer 112 has not yet been deposited). While not wishing tobe bound by a particular theory, it is believed that layering over suchparticles, given the relatively thin nature of the layers, can causestress in the area where the bulges are formed. More particularly, ineach layer, around the perimeter of the bulged region, there can bedefects in the layer, e.g. in the lattice arrangement or on a moremacroscopic level, cracks or voids. One consequence of these defects maybe, for example, an electrical short between electrochromic layer 106and counter electrode layer 110 and/or loss of ion conductivity in layer108. Roll off under the particle is another potential source ofshorting. These defects are not depicted in FIG. 3A, however.

Referring to FIG. 3B, another consequence of defects caused by particle305 is called a “pop-off” In this example, prior to deposition ofconductive layer 112, a portion above the conductive layer 104 in theregion of particle 305 breaks loose, carrying with it portions ofelectrochromic layer 106, ion conducting layer 108, and counterelectrode layer 110. The “pop-off” is piece 310, which includes particle305, a portion of electrochromic layer 106, as well as ion conductinglayer 108 and counter electrode layer 110. The result is an exposed areaof conductive layer 104 at the bottom of the trench left when piece 310popped out of the layered stack of materials. It is believed thatcertain process operations tend to promote pop-offs. One such operationis lithium deposition. FIG. 3C depicts a “large” format particle 320formed in stack 300. Such particle spans the thickness of multiplelayers (in this example electrochromic layer 106, ion conducting layer108, and counter electrode layer 110). While portions of layers 106,108, and 110 form on top of particle 320, they effectively form part ofthe particle itself, which protrudes above the top of layer 110. In somecases, particle 320 naturally pops off without the application of aparticle ejection promoting step such as lithiation. In other cases,particle 320 is removed by use of a particle removal step purposelyapplied to remove particles. Examples of such steps are described belowand include contact adhesion techniques, electrostatic approaches, andthermal or pressure treatments, as well as lithiation, which serve twopurposes.

In some cases, a short type defect is produced underneath an overhangingarea of particle 320. Such defect may result from roll-off of thesubsequently deposited layers, one after the other. For example, thefirst electrochromic layer 106 may extend only a limited distance underthe particle overhang, while ion conducting layer 108 extends a littlefurther under the overhang, counter electrode 110 extends still a littlefurther, and finally, the second transparent conductive layer extendsever further, such that its edge contacts the underlying firsttransparent conductive layer. This conductive layer to conductive layercontact produces a short-type defect. The short exists regardless ofwhether particle 320 ever pops off or is otherwise dislodged. Suchshorts are typically mitigated via circumscription with a laser toisolate the defect and create a small, and more acceptable, pinhole.

Referring to FIG. 3D, and referring back to FIG. 3B, after pop-off andonce conductive layer 112 is deposited, an electrical short is formedwhere conductive layer 112 comes in contact with conductive layer 104.This electrical short would leave a transparent region in electrochromicdevice 300 when it is in the colored state, similar in appearance to thevisual defect created by the short described above in relation to FIG.2.

Pop-off defects due to particles or debris on the substrate, ionconducting layer, and on the counter electrode layer may also causepinhole defects. Also, if a contaminate particle is large enough anddoes not cause a pop-off, it might be visible when the electrochromicdevice is in the bleached state.

The description above, as described in relation to FIGS. 1A, 1B, 2, and3A-3D, presumes that there is a distinct ion conducting (electronicallyresistive) layer sandwiched between an electrochromic layer and acounter electrode layer in electrochromic devices. The description isonly meant to be illustrative of how a particle can create a shortrelated defect. That is, there are electrochromic devices where adistinct electronically resistive and ion conducting layer does notexist, but rather an interfacial region that serves as an ion conductivelayer exists at the interface of the electrochromic and counterelectrode layers. Electrochromic devices having this architecture aredescribed in U.S. patent application Ser. Nos. 12/772,055 filed Apr. 30,2010, Ser. No. 12/772,075 filed Apr. 30, 2010, Ser. No. 12/814,277 filedJun. 11, 2010, Ser. No. 12/814,279 filed Jun. 11, 2010 and Ser. No.13/166,537 filed Jun. 22, 2011, each entitled, “Electrochromic Devices,”each having inventors Wang et al., and each incorporated by referenceherein in their entirety. Thus particles can cause shorting defects inthese devices as well, e.g., where the particle exists at and/or crossesthe interface between the electrochromic and counter electrode layersand/or creates pop-off type defects as described. Such devices are alsosusceptible to other defect types described herein, despite not having adistinct IC layer as in conventional devices.

Thus, three types of defects are of primary concern with regard toelectrochromic windows: (1) visible pinholes, (2) visible shorts, and(3) non-visible shorts. A visible pinhole will have a defect dimensionof at least about 100 μm, and manifest as a very small point of lightwhen the window is colored, sometimes barely discernible to the nakedeye, but visible upon close scrutiny. Typically, though not necessarily,a visible short will have defect dimension of at least about 3micrometers resulting in a region, e.g. of about 1 cm in diameter, whichas mentioned is sometimes referred to as a “halo,” where theelectrochromic effect is perceptibly diminished. These halo regions canbe reduced significantly by isolating the defect causing the visibleshort so that to the naked eye the visible short will resemble only avisible pinhole. Non-visible shorts can affect switching performance ofthe electrochromic device, by contributing to the overall leakagecurrent of the device, but do not create discernible points of light orhalos when the window is in a colored state.

Visible shorts produce a halo when the device is darkened. A halo is aregion in the device where an electrical short across the electrochromicstack causes an area around the short to drain current into the shortand therefore the area surrounding the short is not darkened. Asmentioned, these regions can be up to about 1 cm in diameter, and thuspresent a problem by making the electrochromic window, when colored,unattractive to the observer. This frustrates the purpose of havingwindows that can operate in a colored mode.

Conventionally visible short defects are mitigated after fabrication ofthe electrochromic device, but while still in the production facility,for example, prior to installation in an insulated glass unit. Forexample, individual electrochromic panes are characterized by firstapplying temporary bus bars and then coloring the electrochromic device.Visual defects such as halos are identified and then mitigated, forexample, laser circumscribed to isolate them and remove the halo effect,which leaves smaller, less discernible, pinhole defects. As describedabove, conventionally, at least two, large, dedicated apparatus, areused to carry out identification and mitigation of visual defects.However, defects can form in the electrochromic devices after thedevices leave the production facility due to, for example, the inherentstresses in electrochromic devices (e.g. see above) and/or stressesapplied to the windows during normal use such as installation, pressuredifferential between interior and exterior space, impacts that do notbreak the window pane and the like. Conventionally, for electrochromicwindows already installed in a vehicle or building, mitigating suchdefects would not be done, rather the unit would be replaced in thefield. This can be very expensive.

As mentioned, the methods and devices herein mitigate the effects ofdefects. In one embodiment, the number of visible pinhole defects is nogreater than about 0.04 per square centimeter. In another embodiment,the number of visible pinhole defects is no greater than about 0.02 persquare centimeter, and in more specific embodiments, the number of suchdefects is no greater than about 0.01 per square centimeter. In oneembodiment, the number of short-related defects visible when the deviceis colored is no greater than about 0.005 per square centimeter. Inanother embodiment, the number of short-related defects visible when thedevice is colored is no greater than about 0.003 per square centimeter,and in more specific embodiments, the number of such defects is nogreater than about 0.001 per square centimeter. In a further embodiment,the number of short-related defects visible when the device is coloredis no greater than about 0.0005 per square centimeter. In oneembodiment, the total number of visible defects, pinholes andshort-related pinholes created from isolating visible short-relateddefects, is less than about 0.1 defects per square centimeter, inanother embodiment less than about 0.08 defects per square centimeter,in another embodiment less than about 0.05 defects per squarecentimeter, in another embodiment less than about 0.01 defects persquare centimeter, and in another embodiment less than about 0.045defects per square centimeter (less than about 450 defects per squaremeter of window). In some cases, the total number of visible defects,pinholes and short-related pinholes created from isolating visibleshort-related defects, is less than about 0.005 defects per squarecentimeter.

In some embodiments, the number of non-visible electrical short defectsresults in leakage currents of less than about 20 μA/cm² at ±2V bias.These values apply across the entire face of the electrochromic device(i.e., there is no region of the device (anywhere on the device) havinga defect density greater than the recited value).

In some embodiments, the electrochromic device has no visible defectsgreater than about 1.6 mm in diameter (the largest transverse dimensionof the defect). In another embodiment, the device has no visible defectsgreater than about 0.5 mm in diameter, in another embodiment the devicehas no visible defects greater than about 100 μm in diameter.

Structures with Defect-Mitigating Insulating Layers

Various disclosed embodiments concern the insertion of an additionallayer in the electrochromic device stack. This additional layer servesthe primary role of providing an insulating layer between two conductivelayers that might otherwise short circuit if a particle is ejected fromthe device stack during fabrication or remains on the surface all theway through the fabrication process, leading to roll off shorting. Forexample, if a particle is introduced during fabrication of the firsttransparent conductive layer or the first of the electrochromic andcounter electrode layers, the particle may be ejected prior todeposition of the second transparent conductive layer, which willproduce a short circuit. See rows 2 and 3 of the above table.

In one implementation, a resistive layer, sometimes referred to as adefect-mitigating insulating layer, is deposited at a point in thedevice fabrication process that is after formation of the firsttransparent conductive layer and before formation of the secondtransparent conductive layer. As should be apparent from the abovediscussion, direct contact between two transparent conductive layers ofopposite polarity creates a short circuit. Similarly, direct contactbetween one of the transparent conductive layers and the electrochromicor counter electrode layer having a polarity opposite that of theconductive layer it contacts produces a short circuit. To avoid any ofthese types of short circuit, the defect-mitigating insulating layer isformed after particle ejection that exposes the lower transparentconductive layer or the electrochromic or counter electrode layer ofpolarity opposite that of the upper transparent conductive layer. Theinsulating layer is typically formed prior to formation of the secondtransparent conductive layer. In certain embodiments, the insulatinglayer is deposited in a process operation that is the next operationafter the execution of an operation that has a propensity to causeparticle ejections. In one example, the insulating layer is depositedimmediately after deposition of the first deposited layer of theelectrochromic and counter electrode layers. For example, if theelectrochromic layer is deposited prior to the counter electrode layer,the insulating layer is deposited immediately after the electrochromiclayer is deposited. In such cases, the insulating layer is made from amaterial that is not a conventional ion conducting layer. In anotherexample, the insulating layer is deposited immediately after lithiationof the first deposited layer of the electrochromic and counter electrodelayers. In another example, the insulating layer is depositedimmediately after an ion conducting layer is deposited. In anotherexample, the insulating layer is deposited immediately after the seconddeposited layer of the electrochromic and counter electrode layers. Inanother example, the insulating layer is deposited immediately afterlithiation of the second deposited layer of the electrochromic andcounter electrode layers.

FIG. 4A illustrates one example of an electrochromic device 401 having adefect-mitigating insulating layer 411 disposed in contact with thesecond transparent conductive layer 112 and between conductive layer112and counter electrode layer 110, IC layer 108, electrochromic layer106 as well as first transparent conductive layer 104 Insulating layer411 thus prevents the second transparent conductive layer from shortingto the first transparent conductive layer as well as shorting withelectrochromic layer 106. As shown in FIG. 4A, a stack of layers isformed on a substrate 102. The device has first and second transparentconductive layers 104 and 112 that would short as in the example of FIG.3C except that a defect-mitigating insulating layer 411 is providedbetween them. The composition and other features of layer 411 aredescribed below.

It should be noted that various features of device 401 are effectivelyidentical to those of device 300 in FIG. 3D. Elements of FIGS. 4A, 4B,and/or 4C having the same reference numerals as elements of FIG. 3D maybe considered to be essentially the same elements as their counterpartsin FIG. 3D. It should be understood that implementations including aninsulating layer such as 411 need not employ the stack constructiondepicted in FIG. 4A. For example, various implementations do not includea distinct ion conducting layer 108 as shown. Alternatives to use of adistinct ion conducting layer are described in U.S. patent applicationSer. Nos. 12/772,055, 12/814,279, and 13/462,725, previouslyincorporated by reference.

In some implementations, the counter electrode layer 110 is lithiatedimmediately before the insulating layer 411 is formed. One example of afabrication procedure for forming the structure of FIG. 4A is presentedin FIG. 5B.

Electrochromic layer 106 may contain any one or more of a number ofdifferent electrochromic materials, including metal oxides. Examples ofsuch metal oxides include tungsten oxide (WO₃), molybdenum oxide (MoO₃),niobium oxide (Nb₂O₅), titanium oxide (TiO₂), copper oxide (CuO),iridium oxide (Ir₂O₃), chromium oxide (Cr₂O₃), manganese oxide (Mn₂O₃),vanadium oxide (V₂O₅), nickel oxide (Ni₂O₃), cobalt oxide (Co₂O₃) andthe like. In some embodiments, the metal oxide is doped with one or moredopants such as lithium, sodium, potassium, molybdenum, vanadium,titanium, and/or other suitable metals or compounds containing metals.Mixed oxides (e.g., W—Mo oxide, W—V oxide) are also used in certainembodiments.

In some embodiments, tungsten oxide or doped tungsten oxide is used forelectrochromic layer 106. In one embodiment of the invention, theelectrochromic layer is made substantially of WO_(x), where “x” refersto an atomic ratio of oxygen to tungsten in the electrochromic layer,and x is between about 2.7 and 3.5. It has been suggested that onlysub-stoichiometric tungsten oxide exhibits electrochromism; i.e.,stoichiometric tungsten oxide, WO₃, does not exhibit electrochromism. Ina more specific embodiment, WO_(x), where x is less than 3.0 and atleast about 2.7 is used for the electrochromic layer. In anotherembodiment, the electrochromic layer is WOx, where x is between about2.7 and about 2.9.

In certain embodiments, the tungsten oxide is crystalline,nanocrystalline, or amorphous. In some embodiments, the tungsten oxideis substantially nanocrystalline, with grain sizes, on average, fromabout 5 nm to 50 nm (or from about 5 nm to 20 nm), as characterized bytransmission electron microscopy (TEM).

The thickness of first electrochromic layer 106 depends on theelectrochromic material selected for the electrochromic layer. In someembodiments, the electrochromic layer 106 is about 50 nm to 2,000 nm, orabout 200 nm to 700 nm. In some embodiments, the electrochromic layer isabout 300 nm to about 500 nm. The thickness of the electrochromic layer106 is also substantially uniform. In one embodiment, a substantiallyuniform electrochromic layer varies only about ±10% in each of theaforementioned thickness ranges. In another embodiment, a substantiallyuniform electrochromic layer varies only about ±5% in each of theaforementioned thickness ranges. In another embodiment, a substantiallyuniform electrochromic layer varies only about ±3% in each of theaforementioned thickness ranges.

While not shown in FIG. 4A, the electrochromic and/or counter electrodelayers may be deposited in two sub-layers. In one embodiment, theelectrochromic layer is divided into two sub-layers, one having anominal oxygen concentration and the other having an oxygen-richconcentration. For example, the sub-layer closer to transparentconductive layer 104 contains tungsten oxide having nominal oxygenconcentration and the sub-layer closer to the counter electrode containsa more oxygen rich form of tungsten oxide. Such electrochromic layerdesigns are described in U.S. patent application Ser. No. 12/814,279,previously incorporated by reference.

Referring again to FIG. 4A, in electrochromic stack, an ion conductinglayer 108 overlays first electrochromic layer 106. On top of ionconducting layer 108 is counter electrode layer 110. The counterelectrode layer 110 may be implemented as a second electrochromic layer.In some embodiments, counter electrode layer 110 is inorganic and/orsolid. The counter electrode layer may comprise one or more of a numberof different materials that are capable of serving as reservoirs of ionswhen the electrochromic device is in the bleached state. Thus, thecounter electrode layer serves not only as an ion storage layer, butalso as a complimentary coloring layer.

In some embodiments, suitable materials for the counter electrodecomplementary to WO₃ include nickel oxide (NiO), nickel tungsten oxide(NiWO), nickel vanadium oxide, nickel chromium oxide, nickel aluminumoxide, nickel manganese oxide, nickel magnesium oxide, nickel tantalumoxide, chromium oxide (Cr₂O₃), manganese oxide (MnO₂), Prussian blue.Optically passive counter electrodes comprise cerium titanium oxide(CeO₂—TiO₂), cerium zirconium oxide (CeO₂—ZrO₂), nickel oxide (NiO),nickel-tungsten oxide (NiWO), vanadium oxide (V₂O₅), and mixtures ofoxides (e.g., a mixture of Ni₂O₃ and WO₃). Doped formulations of theseoxides may also be used, with dopants including, e.g., tantalum andtungsten. Because counter electrode layer 110 contains the ions used toproduce the electrochromic phenomenon in the electrochromic materialwhen the electrochromic material is in the bleached state, the counterelectrode preferably has high transmittance and a neutral color when itholds significant quantities of these ions.

In some embodiments, nickel-tungsten oxide (NiWO) is used in the counterelectrode layer (second electrochromic layer). In certain embodiments,the amount of nickel present in the nickel-tungsten oxide can be up toabout 90% by weight of the nickel-tungsten oxide. In a specificembodiment, the mass ratio of nickel to tungsten in the nickel-tungstenoxide is between about 4:6 and 6:4 (e.g., about 1:1). In one embodiment,the NiWO is between about 15% (atomic) Ni and about 60% Ni; betweenabout 10% W and about 40% W; and between about 30% O and about 75% O. Inanother embodiment, the NiWO is between about 30% (atomic) Ni and about45% Ni; between about 10% W and about 25% W; and between about 35% O andabout 50% O. In one embodiment, the NiWO is about 42% (atomic) Ni, about14% W, and about 44% O.

The counter electrode morphology may be crystalline, nanocrystalline, oramorphous. In some embodiments, where the counter electrode layer isnickel-tungsten oxide, the counter electrode material is amorphous orsubstantially amorphous. Substantially amorphous nickel-tungsten oxidecounter electrodes have been found to perform better, under someconditions, in comparison to their crystalline counterparts. Theamorphous state of the nickel-tungsten oxide may be obtained through theuse of certain processing conditions, described below.

In some embodiments, the thickness of the counter electrode is about 50nm about 650 nm. In some embodiments, the thickness of the counterelectrode is about 100 nm to about 400 nm, preferably in the range ofabout 200 nm to 300 nm. The thickness of the counter electrode layer 110is also substantially uniform. In one embodiment, a substantiallyuniform counter electrode layer varies only about ±10% in each of theaforementioned thickness ranges. In another embodiment, a substantiallyuniform counter electrode layer varies only about ±5% in each of theaforementioned thickness ranges. In another embodiment, a substantiallyuniform counter electrode layer varies only about ±3% in each of theaforementioned thickness ranges.

In between electrochromic layer 106 and counter electrode layer 110,there is an ion conducting layer 108. Ion conducting layer 108 serves asa medium through which ions are transported, in the manner of anelectrolyte. That is, when the electrochromic device transforms betweenthe bleached state and the colored state, ions pass through the ionconducting layer. Typically, ion conducting layer 108 is highlyconductive to the relevant ions for the electrochromic and the counterelectrode layers, but has sufficiently low electron conductivity thatnegligible electron transfer takes place during normal operation. A thinion conducting layer with high ionic conductivity permits fast ionconduction and hence fast switching for high performance electrochromicdevices. In certain embodiments, the ion conducting layer 108 isinorganic and/or solid. When fabricated from a material and in a mannerthat produces relatively few defects, the ion conductor layer can bemade very thin to produce a high performance device. In variousimplementations, the ion conductor material has an ionic conductivity ofbetween about 10⁻⁶ Siemens/cm or ohm⁻¹ cm⁻¹ and about 10⁻⁹ Siemens/cm orohm⁻¹ cm⁻¹ and an electronic resistivity between 5×10¹⁰ and 10¹⁴ohms-cm.

Examples of suitable ion conducting layers include silicates, siliconoxides, tungsten oxides, tantalum oxides, niobium oxides, and borates.The silicon oxides include silicon-aluminum-oxide. The tungsten oxidesinclude tungstates. These materials may be doped with different dopants,including lithium. Lithium doped silicon oxides include lithiumsilicon-aluminum-oxide. In some embodiments, the ion conducting layercomprises a silicate-based structure. In other embodiments, suitable ionconductors particularly adapted for lithium ion transport include, butare not limited to, lithium silicate, lithium aluminum silicate, lithiumaluminum borate, lithium aluminum fluoride, lithium borate, lithiumnitride, lithium zirconium silicate, lithium niobate, lithium tungstate,lithium borosilicate, lithium phosphosilicate, and other suchlithium-based ceramic materials, silicas, or silicon oxides, includinglithium silicon-oxide. Any material, however, may be used for the ionconducting layer 108 provided it can be fabricated with low defectivityand it allows for the passage of ions between the counter electrodelayer 110 to the electrochromic layer 106 while substantially preventingthe passage of electrons.

As mentioned, various embodiments do not include a distinct or depositedion conducting layer 108 as shown. In some cases, a transition region orinterfacial region forms between electrochromic and counter electrodelayers deposited in direct contact with one another. Such region may beformed in situ—without depositing a separate ion conducting materiallayer—and possess certain characteristics of a conventional ionconducting layer as described above.

In certain embodiments, one or both of the conductive layers 104 and 112is inorganic and/or solid. Conductive layers 104 and 112 may be madefrom a number of different materials, including conductive oxides, thinmetallic coatings, conductive metal nitrides, and composite conductors.Typically, conductive layers 104 and 112 are transparent at least in therange of wavelengths where electrochromism is exhibited by theelectrochromic layer. Transparent conductive oxides include metal oxidesand metal oxides doped with one or more metals. Examples of such metaloxides and doped metal oxides include indium oxide, indium tin oxide,doped indium oxide, tin oxide, doped tin oxide, zinc oxide, aluminumzinc oxide, doped zinc oxide, ruthenium oxide, doped ruthenium oxide andthe like. Since oxides are often used for these layers, they aresometimes referred to as “transparent conductive oxide” (TCO) layers.Thin metallic coatings that are substantially transparent may also beused. Examples of metals used for such thin metallic coatings includetransition metals including gold, platinum, silver, aluminum, nickelalloy, and the like. Thin metallic coatings based on silver, well knownin the glazing industry, are also used. Examples of nitrides that areconductive in some configurations include titanium nitrides, tantalumnitrides, titanium oxynitrides, and tantalum oxynitrides. The conductivelayers 104 and 112 may also be composite conductors. Such compositeconductors may be fabricated by placing highly conductive ceramic andmetal wires or conductive layer patterns on one of the faces of thesubstrate and then over-coating with transparent conductive materialssuch as doped tin oxides or indium tin oxide. Ideally, such wires shouldbe thin enough as to be invisible to the naked eye (e.g., about 100 μmor thinner).

The function of the conductive layers is to spread an electric potentialprovided by voltage source 116 over surfaces of the electrochromic stackto interior regions of the stack, with very little ohmic potential drop.The electric potential is transferred to the conductive layers thoughelectrical connections to the conductive layers. In some embodiments,bus bars, one in contact with conductive layer 104 and one in contactwith conductive layer 112, provide the electric connection between thevoltage source 116 and the conductive layers 104 and 112. The conductivelayers 104 and 112 may also be connected to the voltage source 116 withother conventional means.

In some embodiments, the thickness of conductive layers 104 and 112 isbetween about 5 nm and about 10,000 nm. In some embodiments, thethickness of conductive layers 104 and 112 are between about 10 nm andabout 1,000 nm. In other embodiments, the thickness of conductive layers104 and 112 are between about 10 nm and about 500 nm. In someembodiments where TEC Glass™ is used for substrate 102 and conductivelayer 104, the conductive layer is about 400 nm thick. In someembodiments where indium tin oxide is used for conductive layer 112, theconductive layer is about 100 nm to 400 nm thick (280 nm in oneembodiment). More generally, thicker layers of the conductive materialmay be employed so long as they provide the necessary electricalproperties (e.g., conductivity) and optical properties (e.g.,transmittance). Generally, the conductive layers 104 and 112 are as thinas possible to increase transparency and to reduce cost. In someembodiment, conductive layers are substantially crystalline. In someembodiment, conductive layers are crystalline with a high fraction oflarge equiaxed grains

The thickness of the each conductive layer 104 and 112 is alsosubstantially uniform. Smooth layers (i.e., low roughness, Ra) of theconductive layer 104 are desirable so that other layers of theelectrochromic stack are more compliant. In one embodiment, asubstantially uniform conductive layer varies by no more than about ±10%in each of the aforementioned thickness ranges. In another embodiment, asubstantially uniform conductive layer varies by no more than about ±5%in each of the aforementioned thickness ranges. In another embodiment, asubstantially uniform conductive layer varies by no more than about ±2%in each of the aforementioned thickness ranges.

The sheet resistance (R_(s)) of the conductive layers may also beimportant because of the relatively large area spanned by the layers. Insome embodiments, the sheet resistance of conductive layers 104 and 112is about 5 to 30 Ohms per square. In some embodiments, the sheetresistance of conductive layers 104 and 112 is about 12 Ohms per square.In general, it is desirable that the sheet resistance of each of the twoconductive layers be about the same. In one embodiment, the two layerseach have a sheet resistance of about 10-15 Ohms per square.

In certain embodiments, the later formed of the counter electrode layerand the electrochromic layer is formed in two operations separated by alithiation operation. After the first portion is deposited and thenlithiated, the insulating layer 411 is deposited. Then the secondportion of the counter electrode (or electrochromic layer) is deposited.FIG. 4B depicts such an embodiment employing an insulating layer toprotect against short circuits resulting from particle ejections. Inthis example, an electrochromic device 403 includes a stack having afirst transparent conductive layer 104, an electrochromic layer 106, anoptional ion conducting layer 108, a counter electrode layer 110 and asecond transparent conductive layer 112, all as described above.Additionally, the device stack includes a defect-mitigating insulatinglayer 411 disposed within the counter electrode layer. As a result, thecounter electrode layer is divided into an inner portion 110 and anouter portion 110′, separated from one another by layer 411. In analternate embodiment, the positions of the electrochromic layer and thecounter electrode layer are reversed, so that the electrochromic layeris split by insulating layer 411 and includes an outer portion 106′ incontact with the second conductive layer 112. Typically, though notnecessarily, the two portions of the counter electrode layer (or counterelectrode layer) are compositionally and/or morphologically alike.

FIG. 4C illustrates an embodiment in which a portion 413 of the counterelectrode serves as an insulating layer. Portion 413 is similar incomposition to the main counter electrode portion 111 but may be moreinsulating, so much so that is can prevent a short between transparentconductive layers 104 and 112 when it is the only layer between them, asshown in the FIG. 4C. Typically, it is at least as insulating as portion111. In some implementations, portion is 413 does not haveelectrochromic properties, while portion 111 does.

As an example, portions 111 and 413 are both nickel tungsten oxidematerials, but portion 413 has a relatively lower ratio of nickel totungsten and/or is deposited under different conditions. In variousembodiments, the main portion 111 of the counter electrode layer isdeposited and then lithiated. Thereafter, the second portion 413 of thecounter electrode layer is deposited. In some implementations, firstportion 111 has a thickness of between about 200 and 500 nm or between250 and 350 nm (e.g., about 280 nm). In some implementations, secondportion 413 has a thickness of about 5-30 nm or about 5-20 nm (e.g.,about 10 nm).

There are many possible implementations of a two portion electrochromiclayer in which one portion serves as a defect-mitigating insulatinglayer. In many implementations, the electrochromic material serving asan insulating layer remains insulating with charge insertion (e.g.,lithium ion or hydrogen ion insertion). In many embodiments, the defectmitigating insulating layer is ionically conductive and accepts andexpels ions as the electrochromic device cycles between optical states.Tungsten oxide is an example of an electrochromic material that becomesionically conductive in certain states of charge. Specifically, tungstenoxide becomes more ionically conductive with increasing concentrationsof lithium ions, increasing in conductivity by orders of magnitude whensignificant concentrations of lithium ions are inserted. For thisreason, tungsten oxide may not serve as an effective defect-mitigationinsulating layer material. By contrast, nickel tungsten oxide remainsionically insulating when lithium ions are inserted and expelled.Therefore, nickel tungsten oxide can serve as both an electrochromiclayer material and a defect-mitigating insulating layer as discussed inthe context of FIG. 4C.

In some implementations, the electrochromic layer and the counterelectrode layer may be switched in the deposition sequence. In someimplementations, for example, the counter electrode is deposited firstand then the electrochromic layer is deposited in portions, with a firstportion being more electronically conductive than a second portion. Alithiation step may be performed between depositions of the two portionsof the electrochromic layer. As in the embodiments presented above, theion conducting layer may be dispensed with in some design stacks.

In some implementations, the first electrochromic layer 106 containstungsten oxide in two sub-layers, each substantially composed of WO_(x).The sub-layer contacting transparent conducting layer 104 has a value ofx that is approximately 2.7-2.8, and the other sub-layer has a value ofx that is approximately 2.85 to 3.5. The counter electrode layer 110contains electrochromic nickel tungsten oxide having a thickness ofabout 50 to 300 nm. The insulating layer 413 also contains nickeltungsten oxide but has different properties as discussed elsewhereherein. In the implementation described here, it has a thickness ofabout 5 to 100 nm. The second transparent conductive oxide may be indiumtin oxide having a thickness of about 200 to 450 nm. The device does nothave a separately deposited ion conducting layer between theelectrochromic layer 106 and the counter electrode layer 111.

In some embodiments, two separate defect-mitigating insulating layersare provided in the electrochromic device. In one example, both theinsulating layers are disposed between the transparent conductivelayers. See first and second conductive layers 104 and 112 in FIG. 4D.In one embodiment, a first insulating layer is disposed in contact withfirst transparent conductive layer 104. In one embodiment, a secondinsulating layer is disposed in contact with second conductive layer112. In the embodiment of FIG. 4D, a first insulating layer 426 isdisposed in contact with first transparent conductive layer 104 and asecond insulating layer 431 is disposed in contact with secondtransparent conductive layer 112. In the device of FIG. 4D, there is noIC layer (e.g., no IC layer 108) disposed between the electrochromiclayer (layer 106) and the counter electrode layer (layer 110). In thedepicted embodiment, the stack is fabricated on a substrate 102. Itincludes first conductive layer 104 in direct or indirect contact withsubstrate 102, first insulating layer 426 in contact with layer 104,electrochromic layer 106 in contact with layer 426, counter electrodelayer 110 in contact with layer 106, second insulating layer 431 incontact with layer 110, and second transparent conductive layer 112(e.g., indium tin oxide). In some embodiments, first transparentconductive layer 104 is a fluorinated tin oxide layer such at TEC.

In certain embodiments, first insulating layer 426 is or contains tinoxide, silicon oxide, nickel tungsten oxide, cerium oxide, aluminumoxide, tantalum oxide, silicon aluminum oxide, and/or titanium oxide. Incertain embodiments, first insulating layer 426 is or contains a metalnitride such as titanium nitride, aluminum nitride, silicon nitride,tantalum nitride, or tungsten nitride. In some cases, first insulatinglayer is or contains titanium dioxide. Carbide, oxynitride, andoxycarbide analogs may also be used. In certain embodiments, firstinsulating layer 426 is or contains a tin oxide layer or titanium oxide,an alumina (aluminum oxide) layer, or layer containing both tin/titaniumoxide and alumina. In some embodiments, first insulating layer 426contains a layer of primary insulating material with voids or gapstherein. Occupying these voids or gaps is another insulating materialsuch a alumina or other material found in a polishing compound. Incertain embodiments, the second insulating layer 431 has a compositionsimilar to that of counter electrode layer 110, but slightly differentin order impart greater resistivity.

In one example, the structure of FIG. 4D includes a layer of titaniumdioxide as a first insulating layer 426 and a layer of non-conductivenickel tungsten oxide as second insulating layer 431. Suitable examplesof nickel tungsten oxide as a defect mitigating insulating layer aredescribed elsewhere herein.

In some cases, glass is provided containing substrate 102, firsttransparent conductive layer 104 and first insulating layer 426. Suchproducts may include TEC (fluorinated tin oxide) layer 104 and titaniumdioxide or tin oxide as layer 426. Examples of such products includeEclipse Advantage™ products from Pilkington. In some cases, thethickness of the defect-mitigating insulating layer is about 10-100 nmthick, or about 15-50 nm thick, or about 20-40 nm thick. A product withhigh quality conductive layers (and optionally a defect-insulatinglayer) such as the TQ product from Pilkington may be used. In thiscontext, high quality layers have relative few defects, relativelycontinuous layers, and/or relatively low roughness in comparison toother products. In one implementation, a substrate containing atransparent conductive layer and a defect-mitigating insulating layer isprovided as is, without polishing, prior to depositing layer 106. Inother implementations, the substrate, including layer 426, is polishedprior to fabricating the remainder of the electrochromic device.

In certain embodiments, the defect-mitigating layer serves toencapsulate and promote adhesion of particles that could be ejected assome point. As shown in FIG. 4E, for example, a defect-mitigating layer461 conformally encapsulates a particle 305. In certain embodiments, thethickness of the defect-mitigating layer is a substantial fraction ofthe size of the average defect-causing particle. For example, a defectmitigating layer that serves to encapsulate particles may be at leastabout 500 nm thick. In some embodiments, an encapsulating layer does notneed to be insulating, and it may be preferable to have it matched tothe properties of the layer it adjoins. Further, if the encapsulatinglayer is between or within counter electrode and/or electrochromiclayers, then the encapsulating layer should permit lithium ion transportand be of a low enough electrical resistance to not prevent electricaltransport to compensate for lithium transport. In certain embodiments,the encapsulating layer is a material identified herein as anelectrochromic or counter electrode material.

The description of FIGS. 4A-4E pertains to electrochromic devices havingat least two distinct layers existing in the device stack. In certainembodiments, the electrochromic device contains only a single layer ofgraded composition that serves the function of an electrochromic devicestack. FIG. 4F depicts one such graded element 421 which is part of anelectrochromic device 413. The electrochromic element 421 is a singlelayer graded composition, having a cathodically coloring electrochromicregion 417, an ion conducting region 418, and an anodically coloringcounter electrode or second electrochromic region, 419. Theelectrochromic element 421 is sandwiched between two transparentconducting layers electrodes 104 and 112. Device fabrication in thisexample may include depositing transparent conductive layer 104 onsubstrate 102, depositing electrochromic element 421 on transparentconductive layer 104, followed by depositing transparent conductive 112on electrochromic element 421. Thus, electrochromic device 413 has onlythree layers, electrochromic element 421 sandwiched between transparentconductive layers 104 and 112. The depicted embodiment also includes adefect-mitigating insulating region 451 located in the secondelectrochromic region 421. Region 451 serves the same purpose as theinsulating layers 411 and 413 in FIGS. 4A-4C. Compositionally, region451 may be similar to or identical to layers 411 and /or 413. It mayalso have a graded composition similar to that of other regions ofelement 421.

A graded electrochromic element may be viewed as a single layerelectrochromic device stack having successive functional regions asopposed to distinct layers where there is an abrupt material changebetween layers and limited material mixing between successive layers.Rather, an electrochromic element has successive functional regionswhere there is significant material mixing between each successivefunctional region. Further details of a compositionally gradedmulti-functional electrochromic element, including fabrication details,are presented in U.S. patent application Ser. No. 13/462,725, previouslyincorporated herein by reference.

While FIGS. 4A-4E show substrate 102 in direct contact with firsttransparent conductive layer 104, this need not be the case. In any ofthe implementations described herein, these layers may be in direct orindirect contact. In some cases, glass substrates are provided withcoatings or layers interposed between glass substrate 102 and firstconductive layer 104. Such coatings may be included for purposes ofimproving thermal properties, transmissivity, blocking diffusion, orother optical properties, providing resistive heating, etc. In oneexample, at least two layers are interposed between substrate 102 andlayer 104. Examples of such materials include silicon oxides and tinoxides. In some cases, the substrate includes a tin oxide layer on topof the main glass substrate, a silicon oxide layer on top of the tinoxide layer, and a fluorinated tin oxide layer on top of the siliconoxide layer.

As illustrated in FIGS. 4A-4E, the defect-mitigating layer(s) may beincluded in the electrochromic device stack at various positions. Anumber of device stack examples are presented below. Each is a variationon the following base stack in which the EC layer is optionally tungstenoxide (or a variant thereof) and the CE layer is nickel tungsten oxide(or a variant thereof):

Base device stack

-   -   First TC layer    -   Electrochromic layer    -   Ion conducting layer (optional)    -   Counter electrode layer    -   Second TC layer

Stacks in which an ion conducting layer is not present

-   -   Option A        -   First TC layer        -   Insulating layer        -   EC layer        -   CE layer        -   Second TC layer    -   Option B        -   First TC layer        -   EC layer        -   Insulating layer        -   CE layer        -   Second TC layer    -   Option C        -   First TC layer        -   EC layer        -   CE layer        -   Insulating layer        -   Second TC layer    -   Option D        -   First TC layer        -   EC layer        -   Partial CE layer        -   Insulating layer        -   Remainder of CE layer        -   Second TC layer    -   Option E        -   First TC layer        -   EC layer        -   Partial CE layer (electrochromic)        -   Remainder of CE layer (non-electrochromic)        -   Second TC layer    -   Option F        -   First TC layer        -   First insulating layer        -   EC layer        -   Second insulating layer        -   CE layer        -   Second TC layer    -   Option G        -   First TC layer        -   First insulating layer        -   EC layer        -   CE layer        -   Second insulating layer        -   Second TC layer    -   Option H        -   First TC layer        -   First insulating layer        -   EC layer        -   Partial CE layer        -   Second insulating layer        -   Remainder of CE layer        -   Second TC layer    -   Option I        -   First TC layer        -   Insulating Layer        -   EC layer        -   Partial CE layer (electrochromic)        -   Remainder of CE layer (non-electrochromic)        -   Second TC layer

Stacks in which an ion conducting is present

-   -   Option A        -   First TC layer        -   Insulating layer        -   EC layer        -   IC layer        -   CE layer        -   Second TC layer    -   Option B        -   First TC layer        -   EC layer        -   Insulating layer        -   IC layer        -   CE layer        -   Second TC layer    -   Option C        -   First TC layer        -   EC layer        -   IC layer        -   Insulating layer        -   CE layer        -   Second TC layer    -   Option D        -   First TC layer        -   EC layer        -   Partial IC layer        -   Insulating layer        -   Remainder of IC layer        -   CE layer        -   Second TC layer    -   Option E        -   First TC layer        -   EC layer        -   IC layer        -   Partial CE layer        -   Insulating layer        -   Remainder of CE layer        -   Second TC layer    -   Option F        -   First TC layer        -   EC layer        -   IC layer        -   Partial CE layer (electrochromic)        -   Remainder of CE layer (non-electrochromic)        -   Second TC layer    -   Option G        -   First TC layer        -   Insulating layer        -   EC layer        -   Insulating layer        -   IC layer        -   CE layer        -   Second TC layer    -   Option H        -   First TC layer        -   Insulating layer        -   EC layer        -   IC layer        -   Insulating layer        -   CE layer        -   Second TC layer    -   Option I        -   First TC layer        -   Insulating layer        -   EC layer        -   Partial IC layer        -   Insulating layer        -   Remainder of IC layer        -   CE layer        -   Second TC layer    -   Option J        -   First TC layer        -   Insulating layer        -   EC layer        -   IC layer        -   Partial CE layer        -   Insulating layer        -   Remainder of CE layer        -   Second TC layer    -   Option K        -   First TC layer        -   Insulating layer        -   EC layer        -   IC layer        -   Partial CE layer (electrochromic)        -   Remainder of CE layer (non-electrochromic)        -   Second TC layer

While each of the above options show the electrochromic layer disposedcloser to the first transparent conductive layer and the counterelectrode layer disposed closer to the second transparent conductivelayer, the order could be reversed in any of the options.

FIG. 4G is a scanning electron micrograph of an electrochromic devicehaving a first transparent conductor layer (TCO) 481 disposed on asubstrate, an electrochromic layer 483 disposed on top of TCO 481, anoptional ion conductor layer 485 disposed on the electrochromic layer, acounter electrode layer 487 disposed on the ion conductor layer, and asecond transparent conductor layer (TCO) 489. FIG. 4G is presented as abaseline structure to show various positions of one or moredefect-mitigating insulating layers as illustrated in FIGS. 4H-4O. FIGS.4H through 4K show devices containing only a single defect-mitigatinginsulating layer and FIGS. 4L through 4O show devices containing twodefect-mitigating insulating layers.

FIG. 4H shows a defect-mitigating insulating layer at a position betweenthe first transparent conductive layer 481 and the electrochromic layer483. FIG. 41 shows a defect-mitigating insulating layer at anintermediate position within electrochromic layer 483. FIG. 4J shows adefect-mitigating insulating layer at an intermediate position withincounter electrode layer 487. FIG. 4K shows a defect-mitigatinginsulating layer at a position between the second transparent conductivelayer 489 and the counter electrode layer 487.

FIG. 4L shows a device with a first defect-mitigating insulating layerat a position between the first transparent conductive layer 481 and theelectrochromic layer 483, and a second defect-mitigating insulatinglayer at an intermediate position within counter electrode layer 487.FIG. 4M shows a device with a first defect-mitigating insulating layerat a position between the first transparent conductive layer 481 and theelectrochromic layer 483, and a second defect-mitigating insulatinglayer at a position between the second transparent conductive layer 489and the counter electrode layer 487. FIG. 4N shows a device with a firstdefect-mitigating insulating layer at an intermediate position withinelectrochromic layer 483, and a second defect-mitigating insulatinglayer at an intermediate position within counter electrode layer 487.FIG. 4O shows a device with a first defect-mitigating insulating layerat an intermediate position within electrochromic layer 483, and asecond defect-mitigating insulating layer at a position between thesecond transparent conductive layer 489 and the counter electrode layer487.

Process Flow Examples

As explained, an insulating layer is deposited at some point in thedevice fabrication process between formation of the first and secondtransparent conductive layers. In certain embodiments, the insulatinglayer is deposited as the next layer after the execution of a processstep that has a significant likelihood of producing a particle ejection.An example of a process step that is likely to eject a particle is theintroduction of lithium metal into the device stack. As discussed below,other process steps can similarly precipitate ejection.

A device fabrication process 501 is depicted in FIG. 5A and represents abaseline process that may be modified to include one or more operationsof depositing an insulating protective layer. Process 501 begins with anoperation 503 where a processing facility or a pre-processing apparatusreceives a substrate. As explained, the substrate may be a window, amirror, or the like. In some implementations, the substrate provided bya substrate vendor contains a transparent conductive oxide layerpre-formed. In other implementations, the substrate is provided withoutthe transparent conductive oxide layer, in which case, the devicefabrication process includes a separate operation of forming thetransparent conductive layer on the substrate.

Continuing with the process flow 501, an operation 505 involves thewashing or otherwise preparing the substrate for device fabrication.This preparation may include such operations as cutting the glass tosize, grinding the edges or other portions of the glass, washing it,tempering it, washing it again, etc. In some implementations, thepreparation operations include first cutting the glass substrate to sizefor the final process, then grinding the edge of the glass, followed bytempering or other strengthening operation. In some cases, the substrateis washed before and/or after tempering. Cutting, grinding and similaroperations are described in U.S. patent application Ser. No. 13/456,056,filed Apr. 25, 2012, which is incorporated herein by reference in itsentirety. Fabrication of the electrochromic device itself begins afterthe pre-processing operation 505 is complete. In certain embodiments,some or all of the device fabrication operations are performed undervacuum or other controlled environmental conditions. For example, an inline fabrication process may involve passing the substrate through aseries of interconnected chambers or stations, each associated with aparticular process operation and each integrated with a vacuum system orother pressure control system. In some embodiments, the integrateddeposition system includes a substrate holder and transport mechanismoperable to hold the architectural glass or other substrate in avertical orientation while in the plurality of deposition stations. Insome cases, the integrated deposition system includes one or more loadlocks for passing the substrate between an external environment and theintegrated deposition system. In another embodiment, the plurality ofdeposition stations include one or more stations for depositing any oneor more of the electrochromic layer, the ion conducting layer, thedefect-mitigating insulating layer, and the counter electrode layer.Sputtering or other physical vapor deposition systems may be used fordepositing any one or more of the individual layers making up theelectrochromic device. A sputtering system may also be used to depositlithium on the device.

Many types of apparatus may be employed to deposit electrochromicmaterials and electrochromic devices in accordance with the embodimentsdisclosed herein. Frequently one or more controllers are employed in theapparatus to control the fabrication process. Those of ordinary skill inthe art will appreciate that processes disclosed herein may employvarious processes involving data stored in or transferred through one ormore computer systems and/or controllers. Certain embodiments relate tothe apparatus, including associated computers and microcontrollers, forperforming these operations. A control apparatus may be speciallyconstructed for the required purposes, or it may be a general-purposecomputer selectively activated or reconfigured by a computer programand/or data structure stored in the computer. The processes presentedherein are not inherently related to any particular computer or otherapparatus. In various embodiments, a controller executes system controlsoftware including sets of instructions for controlling the timing andsequence of the processing steps, processing conditions as describedherein, and the like.

In certain embodiments, the controller contains or executes instructionsfor directing a substrate through a series of deposition stations fordepositing the layers of the electrochromic stack. The controller mayspecify, inter alfa, the rate and direction of substrate transfer, thesputter conditions in any station (e.g., pressure, temperature,sputtering power, and gas flow rates), and the pre- and post-treatmentof a substrate. The controller may include specific instructions forpolishing and otherwise pretreating the substrate prior to deposition.The controller may include specific instructions for substratepost-treatments such as thermal or chemical conditioning. Other computerprograms, scripts, or routines stored on memory devices associated withthe controller may be employed in some embodiments.

Examples of apparatus for fabricating electrochromic devices aredescribed in the following US Patent Applications, each incorporatedherein by reference in its entirety: U.S. Ser. Nos. 12/645,111,12/645,159, 13/462,725, and 12/814,279.

If the substrate provided after pre-processing 505 does not include athin layer of transparent conductive material thereon, devicefabrication begins by forming such layer. If the substrate as providedincludes such layer, it may not be necessary to perform the operation.Regardless of how the transparent conductive material is formed, a firstelectrochromic layer is deposited on it in an operation 507. In certainembodiments, the first electrochromic layer includes a cathodicelectrochromic material. In other embodiments, it includes an anodicelectrochromic material.

In some cases, the substrate is heated prior to deposition of the firstelectrochromic material. The first electrochromic material layer istypically deposited by a process involving physical or chemical vapordeposition under vacuum or other controlled pressure. In a typicalembodiment, the process involves sputtering a target containing elementscontained in the electrochromic layer. However, in alternativeembodiments, the electrochromic layer is deposited under ambientpressure such by a solution phase reaction.

In one implementation, the first electrochromic layer contains acathodically coloring electrochromic material deposited in twooperations, one providing a sub-layer of the base material in a firststoichiometry and the second providing another sub-layer of the basematerial in a second stoichiometry. As an example, the cathodicallycoloring electrochromic material is tungsten oxide, which has a nominalcomposition of WO_(x). The first deposited sub-layer may have acomposition of tungsten oxide in which the value of x is about 2.7 to2.8 and the second deposited sub-layer may have a composition oftungsten oxide in which x is about 2.85 to 3.5. In one example, thefirst sub-layer is thicker; for example, it has a thickness of about 400nm and the second sub-layer has a thickness of about 100 nm.

After the first electrochromic layer is deposited, the partiallyfabricated device is optionally lithiated as indicated at process block509. The lithiation operation involves delivery of lithium metal orlithium ions into the first electrochromic layer. The lithium may beprovided by sputtering or other suitable process. Certain aspects oflithium deposition and the targets used in lithium deposition processesare described in International Application No. PCT/US2012/034556, filedApr. 20, 2012 (designating the US) and in International Application No.PCT/US2012/042514, filed Jun. 14, 2012 (designating the US), both ofwhich are incorporated herein by reference in its entirety.

The next operation in device fabrication process 501 involves depositinga second electrochromic layer (an example of the counter electrode layergenerally described above). See block 511. As with the deposition of thefirst electrochromic layer, this deposition process may be accomplishingusing, e.g., physical or chemical vapor deposition. If the firstelectrochromic layer contains a cathodically coloring electrochromicmaterial, then the second electrochromic layer may contain an anodicallycoloring electrochromic material. The opposite is also true. If thefirst electrochromic layer contains an anodically coloringelectrochromic material, the second electrochromic layer may contain acathodically coloring electrochromic material. In certain embodiments,the second electrochromic layer contains an anodically coloringelectrochromic material such as nickel oxide or nickel doped tungstenoxide (sometimes referred to as NiWO). In some examples, where nickeltungsten oxide serves as the second electrochromic layer, it is formedto a thickness of between about 200 and 300 nm. In some cases, only oneelectrochromic layer is used. Ions are shuttled into and out of thesingle electrochromic layer, from and to a non-electrochromiccounterelectrode.

In the example of FIG. 5A, no ion conducting layer is separatelydeposited between the first and second electrochromic layer. Inalternative embodiments, an ion conducting layer is deposited betweenthese layers. Examples of suitable ion conducting layers include thosepresented above in the description of FIG. 4A.

After the second electrochromic layer is deposited, the device, whichincludes the first and second electrochromic layers, is lithiated asindicated in operation 513. The lithiation may be accomplished asdescribed in the context of operation 509. As mentioned, lithiationoperations may promote ejection of particles previously embedded in thepartially fabricated electrochromic device stack. While not depicted inthe process flow of FIG. 5A, an insulating protective layer may bedeposited after any of the steps that promote ejection of particles.Therefore, in certain embodiments, the deposition of the protectiveinsulating layer may be performed after lithiation operation 509 orlithiation operation 513.

Returning to the process flow depicted in FIG. 5A, after the lithiationof the device in 513, the next process operation deposits a secondtransparent conductive oxide layer as depicted in an operation 515. Atthis point, all structures needed for the basic electrochromic devicehave been created. In some embodiments, there is a subsequent posttreatment of the as deposited device in order to complete the process.See block 517. Examples of suitable post-treatment include thermaland/or chemical conditioning operations. Such operations are describedin U.S. patent application Ser. No. 12/645,111, previously incorporatedherein by reference.

FIGS. 5B-5E present variations on the baseline process depicted in FIG.5A. In each case, the basic process flow from FIG. 5A is depicted butwith additional or different steps for depositing the insulating layerat particular locations in the process. See e.g., operation 521 in FIG.5B and operation 523 in FIG. 5C. In FIG. 5B, the insulating layer isdeposited after lithiation operation 513 and before deposition of thesecond transparent conductive layer (operation 515). In FIG. 5C, theinsulating layer is deposited between lithiation operation 509 anddeposition of the second electrochromic layer (operation 511). Invarious embodiments, the first lithiation and the deposition of theinsulating layer are performed prior to the completion of the firstelectrochromic layer. Both of these deposition operations take placedirectly after a lithiation operation. As explained, the process is notlimited to this sequence. Other operations that may promote particleejection may also trigger deposition of the insulating layer. Also, theinsulating layer may be deposited immediately (or soon) after a stepthat is likely to produce particles or otherwise have particles attachto the substrate surface. In such designs, the defect-mitigating layermay serve to encapsulate such particles.

In some cases, the insulating layer is deposited intermediate betweentwo operations for depositing the second electrochromic layer. Theresulting device may have a structure as depicted in FIG. 4B, forexample. In some cases, a lithiation step is performed after the firstportion of the second electrochromic layer is deposited and before theinsulating layer and the second portion of the second electrochromiclayer are deposited. In other embodiments, the first electrochromiclayer is divided into two portions, with the insulating layer interposedbetween the two portions.

In other embodiments, the second (or first) electrochromic layer isdeposited in two portions, with the second portion serving as thedefect-mitigating insulating layer. An example of a structure resultingfrom such processes is depicted in FIG. 4C and the associateddescription. In some cases, a lithiation operation is performed afterdeposition of the first portion of the electrochromic layer but beforedeposition of the second portion of the layer.

In some implementations such as those of FIG. 4C, the insulating layeractually contains a material having a composition that varies onlyslightly from that of the material of the associated electrochromiclayer. As an example, the second portion of an electrochromic layercontains an insulating material, or at least a material that is at leastas insulating as the first portion of the electrochromic layer. In somecases, the first portion of the layer has electrochromic properties andthe second portion of the layer does not have electrochromic properties.Such embodiments may have multiple benefits. For example, the insulatinglayer will be quite compatible with the material on which it isdeposited. This is because the materials are chemically very similar.

In some embodiments, the second electrochromic layer is a nickeltungsten oxide and the insulating layer is also a nickel tungsten oxide.However, the main portion of the second electrochromic layer and theinsulating layer are deposited under different process conditions. Forexample, while both layers may be deposited by a physical vapordeposition technique employing sputtering from nickel and tungstentargets, the PVD conditions are different. In some cases, the insulatinglayer is deposited at a lower pressure and/or with lower oxygenconcentrations than the electrochromic nickel tungsten oxide layer. Insome cases, the second portion of the insulating layer is deposited at alower power than the second electrochromic layer. Further, the atomicratio of nickel to tungsten may be lower in the insulating layer. Inother cases, the atomic ratio of nickel and tungsten is the same in bothportions of the layer.

In some examples, the ranges of deposition conditions for nickeltungsten oxide electrochromic layer (NiWO1) and insulating layer (NiWO2)are as follows:

NiWO1

1 mTorr<Pressure<50 mTorr

60%<O2%<100% (volume or molar)

0 C<Deposition Temperature<150 C

NiWO2

1 mTorr<Pressure<50 mTorr

40%<O2%<70%

25 C<Deposition Temperature<200 C

In other examples, process conditions used to form each of NiWO1 andNiWO2 are as follows:

NiWO1

5 mTorr<Pressure<15 mTorr (or 7-12 mTorr)

70%<O2%<90% (volume) (or 70-80%)

20 C<Deposition Temperature<60 C

NiWO2

1 mTorr<Pressure<10 mTorr (or 3-7 mTorr)

40%<O2%<60% (or 45-55%)

25 C<Deposition Temperature<60 C

FIG. 5D presents a flow chart for an embodiment employing deposition oftwo separate defect-mitigating insulating layers. The process begins atan operation 531, where a substrate is received having a firsttransparent conducting layer. In certain embodiments, the transparentconducting layer is a fluorinated tin oxide layer that is optionallycovered by an insulating layer of TiO2. Glass substrates having suchproperties are provided by Pilkington of St. Helens, United Kingdomunder the brand name Eclipse Advantage™ for example. The substratereceived in operation 531 may be washed and prepared as described above.See operation 533. Next the process involves forming the firstinsulating layer as indicated at operation 535. This layer may beprepared by many different techniques. As indicated, the substrate maybe provided with both a transparent conductive layer and an insulatinglayer (e.g., fluorinated SnO capped with TiO2). It has been found thatin certain embodiments electrochromic devices perform better whenfabricated on a substrate that has been polished. Such polishing mayinvolve, for example, polishing an upper surface of a TiO2 with apolishing compound containing alumina or other electronically insulatingmaterial. See PCT Patent Application No. PCT/US2012/057606, titled“OPTICAL DEVICE FABRICATION”, and filed Sep. 27, 2012, which isincorporated herein by reference in its entirety. While not wishing tobe bound by theory, the alumina or other insulating material used inpolishing may form an insulating layer on the surface of the firsttransparent (conducting ?) layer or alumina particles may fill in voidsin the tin oxide or other insulating material provided with thesubstrate. In the latter case, the insulating layer contains twodifferent materials, one formed on the substrate as received and theother filling voids in the first material. In other embodiments, thefirst insulating layer formed in operation 535 is deposited by aconventional deposition process such as physical vapor deposition orchemical vapor deposition. The resulting layer may have the compositionof an insulating layer as described elsewhere herein.

After the first insulating layer is formed, the process may continueessentially as described with reference to FIGS. 5B and/or 5C. A firstelectrochromic layer is deposited in an operation 537, followed by anoptional lithiation operation 539. Thereafter, an ion conducting layeris optionally deposited or formed in situ, followed by deposition of asecond electrochromic layer. See operation 541. The device fabricated tothis point is then lithiated as indicated in operation 543. A secondinsulating layer is formed in an operation 545. The material used toform this second insulating layer may be the same or different from thatused to form the first insulating layer in operation 535. If the firstinsulating layer is provided with the substrate received by the processor is provided during polishing, typically the second insulating layerwill have a different composition—or at least a differentmorphology—than the first insulating layer.

After the second insulating layer has been formed, the process depositsa second transparent conductive layer. See operation 547. Thereafter anoptional post treatment is performed as described above. See operation549.

FIG. 5E presents another process of forming a low-defectivityelectrochromic device. The process begins as shown at a block 551 withthe receipt of a substrate having various layers pre-formed thereon.These layers may include one or more diffusion barrier layers such as atin oxide and a silicon oxide layer, a first transparent conductivelayer such as a fluorinated tin oxide layer, and a firstdefect-mitigating insulating layer. As indicated, the defect-mitigatinginsulating layer may include or be titanium oxide, tin oxide, siliconoxide, silicon aluminum oxide, tantalum oxide nickel tungsten oxide,various nitrides, carbides, oxycarbides, oxynitrides, and variants ofany of these, etc.

Upon receiving the substrate, it may be washed and otherwise preparedfor device fabrication as indicated in block 553. As mentioned above,the preparation may include cutting cleaning tempering, etc. Thereafter,as indicated at block 555, the substrate surface is optionally polished.Polishing may be performed with, for example, aluminum oxide, ceriumoxide, or other appropriate polishing material in an appropriate carrierforming a polishing slurry or other appropriate polishing formulation.Polishing may serve various purposes, as explained above. Included amongthese purposes are, for example, reducing the roughness of the surfaceand incorporating insulating material into an insulating surface layerthat might otherwise contain pits, defects, discontinuities, and othersources of potential electrical shorts. The polishing material (e.g.,alumina or cerium oxide) in the polishing compound is itself aninsulating material that fills gaps in an otherwise continuousinsulating layer provided on the substrate.

After the optional polishing, the first and second electrochromic layersare deposited as described above and as indicated in blocks 557 and 561of FIG. 5E. Thereafter, a particle removal steps such as lithiation isperformed as indicated at block 563. Then, a second defect-mitigatinginsulating layer is formed over the second electrochromic layer. Seeblock 565. In a particular implementation of the process depicted inFIG. 5E, the second defect-mitigating insulating layer is aless-electrochromic form of nickel tungsten oxide. In thisimplementation, the second electrochromic layer is an electrochromicform of nickel tungsten oxide. The first electrochromic layer may betungsten oxide deposited in one or more layers. As indicated above, insome implementations, a second tungsten oxide layer formed on top of afirst tungsten oxide layer may have a composition that issuper-stoichiometric in oxygen.

After the second defect-mitigating insulating layer is formed at block565, a second transparent conductive layer is deposited as indicated byblock 567. Thereafter, a post-treatment such as a thermal conditioningor thermal chemical conditioning is performed as described above. Seeblock 569. The process is thus complete for purposes of thisillustration.

The defect mitigating insulating layer may be deposited by a variety oftechniques. Physical and chemical vapor depositions are typical. In somecases, the deposition is conformal; that is, the process deposits aninsulating layer that is able to follow the contours of the pits andother topology variations created by particle ejections. Theconformality of the deposition process should allow the layer to followcontours on the order of micrometers or nanometers (e.g., tens orhundreds of nanometers). Examples of classes of deposition process thatpermit this are chemical vapor deposition techniques and atomic layerdeposition (ALD) techniques. Deposition of device layers performed afterthe insulating layer is laid down may likewise be deposited by aparticularly conformal process.

While lithiation has been presented in most embodiments as the operationthat promotes particle removal, various other techniques may likewiseserve to promote particle removal. One of these is “contact cleaning,” aprocess that involves contacting a layer of a partially fabricatedelectrochromic device with a contact roller, strip, or brush, whichsticks to or attracts particles and then removes them from the device.Typically, contact cleaning employs static attraction and/or adhesion toattract remove particles. Some contact cleaning products arecommercially available, being marketed to the contact sheet cleaning andweb cleaning industries. In various embodiments, a roller mechanism isused. In some cases, two rollers are used: the first one for contactingand removing particles from the device surface and a second roller forcontacting the first roller to remove the particles that were picked upby the first roller in its most recent rotation. Examples of contactcleaning products sold for cleaning bare glass are manufactured byTeknek™ of Renfrewshire, Scotland, UK and Technica.

In some implementations, a contact cleaner is integrated with anelectrochromic device fabrication system. Typically, though not always,the contact cleaner is deployed outside the vacuum environment of thesystem for depositing layers of the electrochromic device. In “cut andcoat” fabrication process flows, a contact cleaner of a single size maybe used. In other fabrication flows, contact cleaners of different sizeare employed for cleaning devices fabricated on glass of differentsizes.

Another category of particle removal techniques rely on differences inthe thermal expansion of particles and the substrate layers in whichthey are embedded. When the particle volume expands or contractsrelative to the surrounding layers, the particles may eject,particularly when the relative volume change is rapid. In someembodiments, a mechanism driving the volume change is irradiation of thesubstrate at wavelength that is selectively absorbed by the particlesbut not the surrounding layer(s), or vice versa. In some embodiments, amechanism driving a relative volume change is a different coefficient ofthermal expansion of the particles and the surrounding layer(s).

Thermal energy may be delivered in various ways. For example, asmentioned, the particles and or the substrate layer(s) may be heated byirradiation. The irradiation may be provided at a wavelength or spectrumof wavelengths from the infrared through ultraviolet ranges. Theirradiation may be provided by one or more lamp, lasers, etc. In oneapproach, a collimated laser beam is passed over a surface of thepartially fabricated electrochromic device. For example, the beam grazesthe surface of the device over the width of the device. The beam maypropagate in a direction perpendicular or substantially perpendicular tothe direction of travel of the substrate carrying the electrochromicdevice. In another approach, a laser beam is focused on the device andmoved in a raster scan over the surface.

In some embodiments, thermal energy is provided by heating the substrateby a non-radiative mechanism such as passing heated gas over the surfaceof the substrate/device and/or passing the substrate/device over aheated element such as a roller. In one implementation, the heatedelement is heated by resistive heating.

In another approach to particle removal, electrostatic force is appliedto the partially fabricated electrochromic device. This may beaccomplished by, e.g., contacting the device with a plasma or applying acharge to the substrate containing the device. In one embodiment, a twostage process is employed. In the first stage, the particles are chargedby exposure to a plasma. Then, in the second stage, the substrate withcharged particles receives an electrical charge, which causes thecharged particles to eject. For example, an electrical contact is madeto a conductive or partially conductive layer of the substrate andcharge is applied to the device through the contact. In someimplementations, the substrate is contacted with a charge of the samesign as the charge applied to the particles by contact with the plasma.

In a further approach, the partially fabricated electrochromic device isexposed to a supercritical fluid such as supercritical carbon dioxide.Supercritical fluids are quite effective at dislodging and removingparticles. The fluid may include a supercritical solvent such assupercritical carbon dioxide with one or more additives containedtherein to improve the cleaning power or other property of the fluid.The supercritical fluid may be brought into contact with the partiallyfabricated electrochromic device using any of a number of processes. Forexample, the device may be immersed or passed through the supercriticalfluid. The fluid itself may be provided in a quiescent or flowing state.In various embodiments, some convection will be employed. For example,the supercritical fluid may flow through a substrate contact chamberdriven by a pump in a recirculation loop. In certain embodiments, thesupercritical fluid is provided as a cryogenic aerosol. The fluid may besprayed on the device as the device or a spray nozzle (or spray gun)moves with respect to the other.

In still another approach, particles are dislodged and/or removed byapplying acoustic energy to the partially fabricated electrochromicdevice. The acoustic energy may be provided at any of a number offrequencies, including megasonic, supersonic, ultrasonic, etc. Incertain embodiments, a vibration source is directly coupled to thesubstrate. In certain embodiments, a vibration source is directlycoupled to a fluid in contact with the substrate/device.

Another removal technique involves ionized air blow off, optionally withan air knife. Yet another technique involves etch-back of a layer of thedevice containing particles. The etch-back may be accomplished with aplasma (e.g., a fluorine or oxygen containing plasma), by using ionmilling, etc. The particles may be removed by the etch-back process ormerely dislodged. In the latter case, a separate particle removaloperation may be applied after etch-back. Such process may include oneor more other process described above such as applying a charge to thesubstrate, contacting the substrate with a supercritical fluid, orselectively heating the particles.

When lithiation is employed as a particle removal technique, it may beimplemented in various formats. For example, the lithium may bedelivered in a single dose or in multiple doses, sometimes to differentlayers of the device, such as to the electrochromic and counterelectrode layers. In some embodiments, all the lithium needed for thedevice is delivered in a single operation. For example, the lithium maybe delivered to the counter electrode layer and allowed to diffuse ormigrate into the remainder of the device. When all lithium is providedin one operation, the incorporation provides maximal volumetric stresson the device and likely provides the most effective way to removeparticles via lithiation. However, the lithiation options are notlimited to a single dose.

The particle removal operation may be performed at various stages in theelectrochromic device fabrication sequence. While the above descriptionhas focused on removal from a partially fabricated electrochromicdevice, it should be understood that any of the removal techniques canalso be performed on a fully fabricated electrochromic device. A numberof process examples are presented below. Each is a variation on thefollowing base process:

Base Device Fabrication Process

-   -   Form first TC layer    -   Form EC layer    -   Form IC layer (optional)    -   Form CE layer    -   Form second TC layer

Processes in which an ion conducting layer is not deposited in aseparate step

-   -   Option 1        -   Form first TC layer        -   Particle removal        -   Form insulating layer        -   Form EC layer        -   Form CE layer        -   Form second TC layer    -   Option 2        -   Form first TC layer        -   Form EC layer        -   Particle removal        -   Form insulating layer        -   Form CE layer        -   Form second TC layer    -   Option 3        -   Form first TC layer        -   Form EC layer        -   Form CE layer        -   Particle removal        -   Form insulating layer        -   Form second TC layer    -   Option 4        -   Form first TC layer        -   Form EC layer    -   Particle removal        -   Form CE layer        -   Particle removal        -   Form insulating layer        -   Form second TC layer    -   Option 5        -   Form first TC layer        -   Particle removal        -   Form EC layer        -   Form CE layer        -   Particle removal        -   Form insulating layer        -   Form second TC layer    -   Option 6        -   Form first TC layer        -   Form EC layer        -   Form partial CE layer        -   Particle removal        -   Form insulating layer        -   Form remainder of CE layer        -   Form second TC layer    -   Option 7        -   Form first TC layer        -   Particle removal        -   Form EC layer        -   Form partial CE layer        -   Form insulating layer        -   Particle removal        -   Form remainder of CE layer        -   Form second TC layer    -   Option 8        -   Form first TC layer        -   Form EC layer        -   Particle removal        -   Form partial CE layer        -   Form insulating layer        -   Particle removal        -   Form remainder of CE layer        -   Form second TC layer

Processes in which an ion conducting layer is deposited in a separatestep

-   -   Option 1        -   Form first TC layer        -   Particle removal        -   Form insulating layer        -   Form EC layer        -   Form IC layer        -   Form CE layer        -   Form second TC layer    -   Option 2        -   Form first TC layer        -   Form EC layer        -   Particle removal        -   Form insulating layer        -   Form IC layer        -   Form CE layer        -   Form second TC layer    -   Option 3        -   Form first TC layer        -   Form EC layer        -   Form IC layer        -   Particle removal        -   Form insulating layer        -   Form CE layer        -   Form second TC layer    -   Option 4        -   Form first TC layer        -   Form EC layer        -   Form IC layer        -   Form CE layer        -   Particle removal        -   Form insulating layer        -   Form second TC layer    -   Option 5        -   Form first TC layer        -   Form EC layer        -   Particle removal        -   Form IC layer        -   Form CE layer        -   Particle removal        -   Form insulating layer        -   Form second TC layer    -   Option 6        -   Form first TC layer        -   Particle removal        -   Form EC layer        -   Form IC layer        -   Form CE layer        -   Particle removal        -   Form insulating layer        -   Form second TC layer    -   Option 7        -   Form first TC layer        -   Form EC layer        -   Form IC layer        -   Form partial CE layer        -   Particle removal        -   Form insulating layer        -   Form remainder of CE layer        -   Form second TC layer    -   Option 8        -   Form first TC layer        -   Form EC layer        -   Particle removal        -   Form IC layer        -   Form partial CE layer        -   Particle removal        -   Form insulating layer        -   Form remainder of CE layer        -   Form second TC layer    -   Option 9        -   Form first TC layer        -   Particle removal        -   Form EC layer        -   Form IC layer        -   Form partial CE layer        -   Particle removal        -   Form insulating layer        -   Form remainder of CE layer        -   Form second TC layer

While each of the above options show the electrochromic layer depositedbefore the counter electrode layer, the deposition order could bereversed in any of the options.

In various embodiments, the particle removal happens within a highresistivity layer of the electrochromic device. In a traditional fivelayer EC device (the base structure above—TC1/EC/IC/CE/TC2), theparticle removal may occur (a) at or after 5% of IC has been depositedbut (b) before or when 95% of the IC has been deposited, and/or (c) ator after 5% of the CE has been deposited, but (d) before or when 95% ofthe CE has been deposited. In certain embodiments, particles are removedand the defect mitigating layer is deposited after a portion of aresistive constituent material (and one that stays resistive even in thepresence of lithium) but before the remainder of the resistive materialis deposited. In a variant of this process, the remainder of theresistive material is the defect-mitigating insulating later. Theparticles that are removed will leave a hole, potentially down to theTC1 layer that will then be filled with the insulating material. Anyparticles that are added in the process of particle removal will alreadyreside on top of the first portion of the resistive component of thedevice and therefore will not pose a threat for short circuits. Notethat tungsten oxide may become conductive in the presence of lithium.Therefore, in certain embodiments employing tungsten oxide as theelectrochromic material, particle removal and deposition of theinsulating layer occur in a layer other than the tungsten oxide layer.

Attributes of the Defect-Mitigating Insulating Layer

In various embodiments, the defect-mitigating insulating layer preventsshort circuits by preventing direct electrical contact between layers ofopposite polarity. In various embodiments, the defect-mitigatinginsulating layer encapsulates particles and prevents them from ejecting.Attributes for the insulating layer may include transparency in thevisible range, weak or no electrochromism, electronic resistancecomparable to or higher than that of undoped electrode material(electrochromic and/or counter electrode), and physical and chemicaldurability.

One of the properties of the insulating layer is its electronicresistivity. Generally, it should have an electronic resistivity levelthat is substantially greater than that of the transparent conductivelayer, often orders of magnitude greater. In some embodiments, theinsulating layer has an electronic resistivity that is intermediatebetween that of a conventional ion conducting layer and that of atransparent conductive layer (e.g., indium doped tin oxide). Thus, theelectronic resistivity should be greater than about 10⁻⁴ Ω-cm(approximate resistivity of indium tin oxide) or greater than about 10⁻⁶Ω-cm. In some cases, it has an electronic resistivity between about 10⁴Ω-cm and 10¹⁴ Ω-cm (approximate resistivity of a typical ion conductorfor electrochromic devices) or between about 10⁻⁵ Ω-cm and 10¹² Ω-cm. Incertain embodiments, the electronic resistivity of the material in theinsulating layer is between about 1 and 5×10¹³ Ω-cm or between about 10²and 10¹² Ω-cm or between about 10⁶ and 5×10¹² Ω-cm, or between about 10⁷and 5×10⁹ Ω-cm. In some embodiments, the defect mitigating insulatinglayer material will have a resistivity that is comparable (e.g., withinan order of magnitude) of that of the electrochromic layer of counterelectrode material.

The resistivity of the material is coupled to the thickness of theinsulating layer. This resistivity and thickness level will togetheryield a sheet resistance value which may in fact be more important thansimply the resistivity alone. (A thicker material will have a lowersheet resistance.) When using a material having a relatively highresistivity value, the electrochromic device may be designed with arelatively thin insulating layer, which may be desirable to maintain theoptical quality of the device. In certain embodiments, the insulatinglayer has a thickness of about 100 nm or less or about 50 nm or less. Inone example, the insulating layer has a thickness of about 5 nm, inanother example, the layer has a thickness of about 20 nm, and inanother example, the layer has a thickness of about 40 nm. In certainembodiments, the electronic sheet resistance of the insulating layer isbetween about 40 and 4000 Ω per square or between about 100 and 1000 Ωper square. In some cases, the insulating material is electricallysemiconducting having a sheet resistance that cannot be easily measured.

In certain embodiments, particularly those in which a defect-mitigatinginsulating layer is disposed on a substrate, a thicker layer issometimes employed. The thickness may be, for example, between about 5and 500 nm, or between about 5 and 100 nm, or 10 and 100 nm, or betweenabout 15 and 50 nm, or between about 20 and 50 nm, or between about 20and 40 nm.

In certain embodiments, the material making up the insulating layer hasa relatively low blind charge capacity. In the context of anelectrochromic device, a material's charge capacity represents itsability to reversibly accommodate lithium ions during normalelectrochromic cycling. Blind charge capacity is the capacity of thematerial to irreversibly accommodate lithium ions that it encountersduring fabrication or during initial cycling. Those lithium ions thatare accommodated as blind charge are not available for subsequentcycling in and out of the material in which they are sequestered. If theinsulating material has a large charge capacity, then it may serve as areservoir of nonfunctional lithium ions (typically the layer does notexhibit electrochromism so the lithium ions that pass into it do notdrive a coloring or bleaching transition). Therefore, the presence ofthis additional layer requires additional lithium ions to be provided inthe device simply to be taken up by this additional layer. This is ofcourse a disadvantage, as lithium can be difficult to integrate into thedevice during fabrication.

In certain embodiments, the charge capacity of the defect-mitigatinginsulating layer is between about 10 and 100 milliCoulomb/cm²*μm; e.g.,between about 30 and 60 milliCoulomb/cm². For comparison, the chargecapacity of a typical nickel tungsten oxide electrochromic layer isapproximately 120 milliCoulomb/cm²*μm. In certain embodiments, the blindcharge capacity of the defect-mitigating insulating layer is betweenabout 30 and 100 milliCoulomb/cm²*μm; e.g., between about 100 and 110milliCoulomb/cm²*μm. For comparison, the charge capacity of a typicalnickel tungsten oxide electrochromic layer is typically less than about100 milliCoulomb/cm²*μm.

In certain embodiments, the defect mitigating insulating layer isionically conductive. This is particularly the case if the layer isdeposited before the second of the two electrodes (electrochromic andcounter electrode). In certain embodiments, the defect mitigatinginsulating layer has an ionic conductivity of between about 10⁻⁷Siemens/cm and 10⁻¹² Siemens/cm, or between about 10⁻⁸ Siemens/cm and10⁻¹¹ Siemens/cm or between 10⁻⁹ Siemens/cm and 10⁻¹⁰ Siemens/cm

In certain embodiments, the defect mitigating insulating layer has adensity of at most about 90% of the maximum theoretical density of thematerial from which it is fabricated.

In some implementations, the insulating layer exhibits little or noelectrochromism during normal operation. Electrochromism may be measuredby applying a defined voltage change or other driving force andmeasuring the change in optical density or transmissivity of the device.

The material of the insulating layer should also possess good opticalproperties. For example, it should have a relatively low opticaldensity; for example, below about 0.1 or below about 0.05. Additionally,the material may have a refractive index that matches that of adjacentmaterials in the stack so that it does not introduce significantreflection. The material should also adhere well to other materialsadjacent to it in the electrochromic device stack.

As mentioned, the defect-mitigating layer may serve to encapsulateparticles that deposit on the device during fabrication. Byencapsulating these particles, they are less likely to eject. If this isa goal, then the operation of depositing the defect-mitigating layershould be performed immediately or soon after the process operation oroperations that likely introduces particles into the device stack.Further, if a goal is to encapsulate, then thicker layers are desirable.

Various materials may be used as defect-mitigating insulating layers.These include various transparent metal oxides such as aluminum oxide,zinc oxide, tin oxide, silicon aluminum oxide, silicon oxide, ceriumoxide, stoichiometric tungsten oxide (e.g., WO₃, wherein the ratio ofoxygen to tungsten is exactly 3), variations of nickel tungsten oxide,and highly oxidized indium tin oxide (ITO). In some cases, theinsulating material is selected from aluminum oxide, zinc oxide, siliconaluminum oxide, tantalum oxide, and nickel tungsten oxide (typically anon-electrochromic type). In addition, some nitrides, carbides,oxynitrides, oxycarbides, and fluorides having medium to high resistanceand optical transparency can be used. For example, nitrides such astitanium nitride, tantalum nitride, aluminum nitride, silicon nitride,and/or tungsten nitride may be used. Further, carbides such as titaniumcarbide, aluminum carbide, tantalum carbide, silicon carbide, and/ortungsten carbide may be used. Oxycarbides and/or oxynitrides may also beused in certain embodiments. Unless otherwise specified, each of thesecompositions may be present in various stoichiometries or ratios ofelements. For insulating layers containing nickel and tungsten, theratio of nickel to tungsten may be controlled such that relatively highratios are employed. For example the Ni:W (atomic) ratio may be betweenabout 90:10 and 50:50 or between about 80:20 and 60:40.

In some cases, the material chosen for the defect-mitigating layer is amaterial that integrates well with electrochromic stack. The integrationmay be promoted by (a) employing compositions similar to those ofmaterials in layers adjacent to insulating layer in the stack (promotesease of fabrication), and (b) employing materials that are opticallycompatible with the other materials in the stack and reduce qualitydegradation in the overall stack.

Although the foregoing invention has been described in some detail tofacilitate understanding, the described embodiments are to be consideredillustrative and not limiting. It will be apparent to one of ordinaryskill in the art that certain changes and modifications can be practicedwithin the scope of the appended claims.

What is claimed is:
 1. An electrochromic device comprising: a firstelectrode layer disposed on a substrate, the first electrode layercomprising a first transparent electronically conductive material; anelectrochromic stack on the first electrode, the electrochromic stackcomprising an electrochromic layer of electrochromic material and acounter electrode layer of counter electrode material; a secondelectrode layer over the electrochromic stack, the second electrodelayer comprising a second transparent electronically conductivematerial; and a defect-mitigating insulating layer sealing a pop-offdefect in the electrochromic device stack; wherein the defect-mitigatinginsulating layer comprises a substantially transparent andelectronically insulating material, and wherein the defect-mitigatinginsulating layer contacts the first electrode layer at the pop-offdefect.
 2. The electrochromic device of claim 1, wherein thedefect-mitigating insulating layer contacts at least the electrochromiclayer and the counter electrode layer at the pop-off defect.
 3. Theelectrochromic device of claim 1, wherein depositing thedefect-mitigating insulating layer prevents electronically conductinglayers and/or electrochromically active layers of the device fromcontacting layers of the opposite polarity and creating a short circuitin the region of the pop-off defect.
 4. The electrochromic device ofclaim 1, wherein the electrochromic stack comprises lithium.
 5. Theelectrochromic device of claim 1, wherein the electronically insulatingmaterial of the defect-mitigating insulating layer is a metal oxide, ametal nitride, a metal carbide, a metal oxynitride, or a metaloxycarbide.
 6. The electrochromic device of claim 1, wherein theelectronically insulating material of the defect-mitigating insulatinglayer is selected from the group consisting of: (a) cerium oxide,titanium oxide, aluminum oxide, zinc oxide, tin oxide, silicon aluminumoxide, tungsten oxide, nickel tungsten oxide, tantalum oxide, andoxidized indium tin oxide; (b) titanium nitride, aluminum nitride,silicon nitride, tungsten nitride; (c) titanium carbide, aluminumcarbide, silicon carbide, tantalum carbide, and tungsten carbide; and(d) silicon oxynitride.
 7. The electrochromic device of claim 1, whereinthe defect-mitigating insulating layer is between about 5 nm and 500 nmthick.
 8. The electrochromic device of claim 1, wherein thedefect-mitigating insulating layer is between about 10 nm and 100 nmthick.
 9. The electrochromic device of claim 1, wherein theelectronically insulating material of the defect-mitigating insulatinglayer has an electronic resistivity of about 10⁻⁴ Ω-cm to 10¹⁴ Ω-cm. 10.The electrochromic device of claim 1, wherein the electronicallyinsulating material of the defect-mitigating insulating layer has anelectronic resistivity of about 10⁶ to 5×10¹² Ω-cm.